Add Android PagerSlidingTabStrip library, an Interactive paging indicator widget This library can be found at https://github.com/astuetz/PagerSlidingTabStrip/ and we currently use the v1.0 tag

ContactList: Separate creation of ContactListAdapter and managment of the group list This is two separate things. getContactListAdapter is called in ContactListFragment.onActivityCreated() which is during a fragment transaction. Management of the group list calls FragmentPagerAdapter.notifyDataSetChanged() which repopulate the FragmentPagerAdapter and to do so calls FragmentManager.executePendingTransactions() in a recursive way and is not allowed (IllegalStateException).