Include git and Maven for JRuby containers.
Add Octave Docker containers. Fixes #50.
Add tesseract Docker container. Fixes #57.
Add PhantomJS Docker container. Fixes #37.
Add SlimerJS Docker container. Fixes #38.
Include bzip in PhantomJS, SlimerJS installation dependencies.
Add Vowpal Wabbit Docker container. Fixes #44.
Issue #31: Test statsd Docker container.