EGORefreshTableHeaderView.m

Add an delay invoke in message egoRefreshScrollViewDidEndDragging:,cause when we use it in some multi-thread app,it may lead to the endless loop(under loading state...). Message [self setState:EGOOPullRefreshNormal] (in egoRefreshScrollViewDataSourceDidFinishedLoading:) will be called firstly before [self setState:EGOOPullRefreshLoading] , so we'll run [self setState:EGOOPullRefreshLoading] finally. Then we'll under loading state.