Updated Visibility and Animation Duration functioanlity
Added IllegalArgumentException to setAnimationDuration
Merge pull request #23 from JesseFarebro/master

Updated Animation Duration Visibility, Added Animation Duration Setter as well as isAnyItemExpanded
Added auto-scroll of hidden expanded items into the visible area
Reusing getAnimationDuration() for animation duration
Merge branch 'master' of https://github.com/naddaf/Android-SlideExpandableListView.git