[Android] Isolate fragment management for children of MasterDetailPage (#136)

[Android] Isolate fragment management for children of MasterDetailPage  (#136)

* Isolate fragment management for children of MasterDetailPage in AppCompat
If a MasterDetailPage hosts NavigationPages or TabbedPages in either the
Master or Detail sections, wrap those pages in their own Fragment (and
ChildFragmentManager) to isolate their Fragment management operations and
avoid recursive entry into the executePendingTransactions method
Also fix a disposal bug in the custom MDP renderer in Control Gallery

* Remove MDP Split setting that breaks test on iPad