Add ability to hide scrollbar

Sometimes you may want to not have the scrollbar visible (IE: 2 or more linked waveforms on the page controlled by a single scrollbar).  The "hideScrollbar" option (default=false for backward compatibility) allows for this
Add ability to hide scrollbar
Fix "interact" access methods

enableInteration(), disableInteraction(), toggleInteraction() were broken when .interact in Drawer was removed, and changed to access only via params.interact.
Merge pull request #227 from rgagnon24/master

Add ability to hide scrollbar