Add the class abourt gif generate

note： the tree class is come from github
Add workset activity but no implement

The workset is the works of users
When user combine the pictures in a group
Add workset_Gallay

3个小时的成果，比较满意，虽然没能用loader加载，
虽然最终也没显示动画，不过一切都很容易了
Gallary完成， 支持动画! loader异步加载！ 很棒，但是布局有严重问题，GifView的size也有严重问题。
ViewPicture is implemented using ViewPager, It's so nise.
Remvoe the unused import
Replace the ImageView with MengView
Change the implement of some fuctions abount adding picture to a
group,make it more general.
Fix bug, crash when coming from group list