Merge pull request #7 from kununu/rename-fade. fixes #4

rename fade class

* kununu/rename-fade:
  minified version of polyfill
  add grayscale-fade class to settings
  remove old ```.grayscale.fade``` class
  add grayscale-fade to js shim
  rename grayfade to grayscale-fade
  update documentation, demo and minified js
  rename fade class to grayfade to resolve conflict with bootstrap (still compatible with fade)