Alpine update to 3.14

'ttf-ubuntu-font-family' was remove from Alpine

Use black as formatter for python files

Fix building cryptography pip

NetBox should always be referred to as NetBox ...

Fix all instances of "Netbox".

```Shell
git ls-files -z . | xargs --null -I '{}' find './{}' -type f -print0 | xargs --null sed --in-place --regexp-extended 's#Netbox#NetBox#g;'
```

Ref: https://netbox.readthedocs.io/en/stable/development/style-guide/#branding

Gunicorn is replaced with nginx-unit ...

We now serve Netbox with an nginx-unit instance instead of Gunicorn.
This allows us to get rid of the extra Nginx container because Unit is
also serving the static files. The static files are now collected at container
buildtime instead of every startup.

Dynamically load configuration files

Merge pull request #274 from tobiasge/optimise-builds ...

Optimise builds

Dockerfile: Fixed file permissions for media

Add checks to verifiy if a new build is needed ...

This checks if the source materials (python image, Netbox commit,
netbox-docker commit) have changed since the last build. This check is done
by comparing the digest and commit ids from the previous image with the
given tag to the current values taken from the Git and Docker repositories.

The checks are only performed for builds by the automated builds on Github.

Prepare for Netbox 2.7

Merge pull request #186 from netbox-community/non-root ...

Non root

Revert "Fix #179 'libc not found'" ...

This reverts commit feb810a.

Remove the named user, change permissions to 'g+w'

Adds netbox user

Adds more labels to the Dockerfile ...

It also updates the README and the bug_report template to reflect
the changes. Additionally, in the README some relevant shields from
shields.io are added.

The labels follow [label-schema.org][lsorg] and the [OpenContainer
image spec, section annotations][ocis], specifications.

[lsorg]: http://label-schema.org/rc1/
[ocis]: https://github.com/opencontainers/image-spec/blob/master/annotations.md

Fix #179 'libc not found' ...

Gunicorn version 20 crashes in this docker image. So for now use a
version <20.

Optimize pip install command ...

As mentioned by @sdktr the "--install-option" is redundant. The added
"--no-warn-script-location" is used to silence warnings when installing
into a directory that is not on $PATH.

Fixes #170 - "drf-yasg" installed into wrong dir ...

With the new multistage build the pip install command put some packages
in the wrong directory. This resuled in them not being copied into the
runtime images. This commit add the additional "--prefix" option to the
install command. After that all test run and we no longer get the error
"ModuleNotFoundError: No module named 'drf_yasg'".

Remove trailing space in Dockerfile

Checkout the repository with git ...

This changes the build process even further. Instead
f using `wget` to fetch the current code, `git` is used.
This allows for faster switching between branches,
because only the differences between them have to be
fetched from the server.

But the main advantage is that the build cache can
finally be used as designed by Docker. Repetitive
builds are very fast now. This is also true between
branches and tags, as long as the `requirements.txt`
file doesn't change.

externalize netbox download with wget

Refactor to multistage builds ...

This commit introduces a huge change in the build process.

What changed:

- Dockerfile.ldap was integrated into Dockerfile as a seperate
  [build stage][multistage-build].
- All the build scripts were refactored according to this.
- The `docker-compose.yml` file was adjusted likewise.
- The main build script, `/build.sh`, now always builds all
  targets (formerly called variants).
- The minimal requirements for Docker and docker-compose
  have increased.
- The build on hub.docker.com must be adjusted.

This change should also fix #156 permanently.

[multistage-build]: https://docs.docker.com/develop/develop-images/multistage-build/

fix AttributeError for ruamel.yaml

Update base image ...

This updates the base image to Alpine 3.10 with Python 3.7

%s/digitalocean/netbox-community/gi ...

Thank you Digitalocean for sponsoring Netbox!
And thank you for letting it grow up and move out ;)

Explain caching strategy in Dockerfile comments

Changing REF_URL to use HEAD/TAG agnostic API ...

Per [dicsuccion](https://github.com/netbox-community/netbox-docker/pull/137#issuecomment-495667921) with @cimnine, changing the API endpoint to one that retains functionality of previous URL while supporting both HEADS and TAGS

Adding REF to GitHub repo HEAD for cache busting ...

After installing requirements, check if  HEAD has changed and bust cache for RUN instruction for wget  archive

Caching of requirements.txt ...

After [a discussion][1] with rje6459 on the networktocode Slack
in the #netbox-docker channel we've come up with a small improvement
to those that regularly have to build netbox docker locally.

It fetches the "requirements.txt" from the desired branch before
downloading netbox itself.

[1]: https://networktocode.slack.com/archives/CD23LP8BC/p1558537080023200