New build supporting multiple languages

This pull request has:

- support for multiple languages
- support for markdown content files (none present yet, but tested)
- html content files
- wires the build up to existing (albeit out of date) Spanish language content
- more robust readme with detailed information on the above modifications

This touches on tickets #32, #20, #12, #37

Note: there may be some remnants of Jekyll related bits in some of these GEM files etc., but not being a Ruby dev I wasn't sure what was added and what wasn't by Jekyll specifically.