chore(core): Added core module and ariaHelper service
chore(smButton): Added generic sm-button directive
chore(smButton): Improved smButton directive after review
chore(smButton): Added unit tests
refactor(smButton): Use  to manage css classes
test(smButton): Removed useless test
Merge pull request #4 from Semantic-Org/semantic-ui-elements-button

Semantic-UI-Angular:  sm-button  directive