Move settings that don't differ per container to the top level
Raise proxy_buffering statement to http level
Make template more readable

* $value -> $container
Drop unused index variables from range statement
Move gzip_types, access_log, and error_log to http
Merge pull request #49 from md5/reduce-redundancy

Simplify template output
Optimize Dockerfile.

This optimizes the Dockerfile by;

- Combining RUN statements so that files are removed in the
  same layer as they are added.
- Removing the downloaded .tar.gz of the docker-gen binary
  after expanding
- Adding `--no-install-recommends` (but explicitly installing
  ca-certificates)
- Replacing `ADD` with `COPY` (recommended if no unpacking is
  required)

Also added a `.dockerignore` file to prevent the `.git` directory
and README.md being added to the image.

These changes reduce the size of the image with 34 MB (was 268.4 MB,
now 233.9 MB), and results in less layers being produced.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Merge pull request #52 from thaJeztah/optimize-dockerfile

Optimize Dockerfile.