Fixes keyboard event and Added alt text.

- override onKeyDown method to fix tab and arrow key press events.
- added alt Text to confidenceSlider-item-handle.
fixes alt text change.

- fixes alt text change on click of confidenceSlider-item-outer-bar
Merge pull request #12 from hrajotia/develop

Fixes keyboard event and Added alt text.
fixed showFeedback method and slider issue.

- fixed showFeedback method.
- fixed slider goes out of max sliding value when interacting using
keyboard.
Merge pull request #13 from hrajotia/develop

fixed showFeedback method and slider issue
Bower elements for editor
Merge pull request #17 from adaptlearning/bower-editor-values

Bower elements for editor
update _buttons object
Merge pull request #18 from thomaseitler/develop

update _buttons object