Update _mixins.scss to fix $rotation sass var (#2429)

This should fix #2429 [FortAwesome#2429].
Merge pull request #2431 from luke83/patch-2

Update _mixins.scss to fix $rotation sass var (#2429)
Rebuilt assets
referenced .min.css file for CDN

put on dev branch per #2485
ensure PR on the dev branch

prevents re-submittals
Update README.md

Added contributing section
hand-deleted changes

[Better update](https://github.com/FortAwesome/Font-Awesome/commit/c67253b626fbdea09357721aa2a21bb7f956d6db)
Merge pull request #2489 from tomByrer/4.0.4-wip

referenced .min.css file for CDN
Remove -ms-keyframes
Merge branch '4.0.4-wip' of github.com:FortAwesome/Font-Awesome into 4.0.4-wip

* '4.0.4-wip' of github.com:FortAwesome/Font-Awesome:
  hand-deleted changes
  Update README.md
  ensure PR on the dev branch
  referenced .min.css file for CDN
Merge pull request #2495 from nielsenramon/4.0.4-wip

Remove -ms-keyframes
Merge branch '4.0.4-wip' of github.com:FortAwesome/Font-Awesome into 4.0.4-wip

* '4.0.4-wip' of github.com:FortAwesome/Font-Awesome:
  Remove -ms-keyframes
Bumped version to 4.0.4
Rebuilt assets
changing fa-asc and fa-desc names to address a naming error. #2473
upgrading docs to bootstrap 3.0.2
changing tagline
change from component.json to bower.json
Merge pull request #2526 from wazoo/4.0.4-wip

change from component.json to bower.json
Update bower.json

Added new line at the end of the file
Adding .less file extension to imports to increase compatibility
Closes #2512