Merge pull request #1 from AlexLarra/master

add Rmagick to Imagery
add Third-party section and some styling changes
Web servers and descriptions for Testing section
add Video and OAuth sections; ++ links and descriptions
add Error Handling section
update links and descriptions
add Markdown Processors
add Assets and Core extensions categories
a couple more to Misc
add ruby-gmail and Rugged
update descriptions
Rake, of course
add Git Tools section, add Vagrant to DevOps
Add CocoaPods, Sunspot and Mailman; add a nice badge
add Better Errors and Play
Add File Upload section
Add factory_girl to Testing section
add MailCatcher to Email section
add Scheduling section, add Pliny and Roar to API Builder
add Profilers section