Add missing dependencies to production Docker image

[AndrewKvalheim]

Checklist

• I have read the Contribution & Best practices Guide.
• My branch is up-to-date with the upstream master branch.
• The tests pass locally with my changes.
• I have added tests that prove my fix is effective or that my feature works(if appropriate).
• I have added necessary documentation (if appropriate).

Short description of what this resolves

As of 6648082 the Docker base image no longer includes Bundler and Foreman:

@@ -25,11 +26,7 @@
 # Disable versioned gem binary names
 RUN echo 'install: --no-format-executable' >> /etc/gemrc
 
-# Install bundler & foreman
-RUN gem install bundler:1.17.3 foreman
-
 # Create our user
 RUN useradd -m --user-group osem

These dependencies are installed in the application image instead:

osem/Dockerfile

Lines 19 to 20 in 3c2a082

	# Install bundler & foreman
	RUN sudo gem install bundler:1.17.3 foreman

The production Dockerfile is missing them, causing its build to fail:

bundle: command not found

Changes proposed in this pull request

Add the dependencies to the production Dockerfile as well.