Bugfix （When zero cells，Add to crash）

when remove all items in collectionView ,then press Add button,will be
crash.
Refresh Method Implement

when i press reload button,nothing happened,i think it should be resign
first look.so ,i change some code for it.
Merge pull request #22 from maljaiun/master

Fix Add bug (when remove all items)  && reimplement refresh methods on reload button.