feat(Gruntfile.coffee): More information in SauceLabs test task

The tags for unit tests now always contain the current SAUCE_USERNAME,
 and a `build` option was added per SauceLab's recommendation in order
 to generate the correct badge.
fix(README.md): Point badge to FineUploader's account

For some reason it was pointed to my own SL account.
fix(.travis.yml): Improved regex

Better matching for ensuring tests only occure on master, develop,
feature, and hotfix branches.
Merge branch 'feature/sauce-badge' into develop

fixes #914