Merge pull request #21 from ReactiveX/develop

Develop (merging PR #19)
Merge pull request #24 from ReactiveX/develop

merging PR #22 and #23 to master
Fixed Rakefile condition
Drafted frontpage parts, and make first section header
Minor improvements to the Observable section on the frontpage
Drafted the list of famous Rx users
Icons wand, join, ear, for headers CREATE, COMBINE, LISTEN
New background image for jumbotron on frontpage
Refactor styles from frontpage to frontpage-diagram.less
Drafted the Ubiquitous section
Drafted the remaining sections on the frontpage
Wrote content for Ubiquitous frontpage section
Drafted 'Better code' section'; added horizontal lines
Finished "Better codebases" frontpage section
Built the frontpage logos section
Merge pull request #27 from staltz/frontpage

Major restyle of the frontpage
Merge branch 'frontpage' into develop
Merge branch 'develop'
Fix logo link to Microsoft Rx Codeplex
Merge pull request #28 from staltz/master

Fix logo link to Microsoft Rx Codeplex