Tweak MVC diagram link in Workshop site

[Fixes #386]
bundle update and remove unused md2step file
added alt text to images
Merge branch 'alt-text-frontend' of https://github.com/adowns01/docs into adowns01-alt-text-frontend
Serve font-awesome out of a gem instead of vendoring it

This is some pretty hacky stuff, and could probably be written
a little better to send out good cache headers and other nice things.
But at that point, we might as well just start using Sprockets?
Load SCSS files into one combined application.css using Sprockets
Load font-awesome in a more natural manner with Sprockets

Start sprocketsing an application.js
Load jQuery from a gem instead of checking it in
Load bootstrap JS (hopefully only Dropdown) from a gem
Load fonts in application.css
Refer to Boston chapter in build status and deploy URL

All other references to the main RailsBridge organization can stay as long as
the material we're actually using points back to our own stuff.
Set aside original Installfest material
Bring over Downloads and Installfest pages from Boston

We're going to temporarily replace the original Installfest material with the
Boston version, which involves setting up virtual machines.
Bring over styles for installation-by-OS tables
Use shorthand Markdown file extension
Put Downloads under Setup section in top nav links
Add Decklin's Command Line slides
Clean up Downloads and Installfest content

This includes:
* Updating Titleizer class to handle hypenated file names and other acronyms
* Rearrange some content for better flow now that we have a sidebar nav to
outline steps
* Modifying link syntax to determine where a page is part of the flow or
extraneous/optional (HTML vs. Markdown) since sidebar is auto-generated
Link to Boston's website and GitHub pages
Final version of 2014-09 VM