add animatorOffset for PullToRefresher which can adjust the position …

…of animator

删除contentInsetType的设定，过于累赘，意义不大

优化接口

change enableXXX to isXXXEnabled

optimize gif animator

version2.0.1

Merge pull request DanisFabric#10 from brightsider/master

Migration to Swift 3

for swift 2.2

fix arrow control back color

support edit color