Remove dependency upon FragmentActivity

The FragmentManagerImpl is intimately tied with a FragmentActivity. In
many cases, we want to be able to create / manage Fragments outside of
a FragmentManager. This defines a FragmentController interface that can
be used by any class to host Fragments.

Bug: 19569096
Change-Id: I62dee733a70577d0d3c8f96a89e4b05a3d5e18b0

• .gitignore[diff]
• v4/AndroidManifest.xml[diff]
• v4/api/current.txt[diff]
• v4/java/android/support/v4/app/BackStackRecord.java[diff]
• v4/java/android/support/v4/app/DialogFragment.java[diff]
• v4/java/android/support/v4/app/Fragment.java[diff]
• v4/java/android/support/v4/app/FragmentActivity.java[diff]
• v4/java/android/support/v4/app/FragmentContainer.java[Added - diff]
• v4/java/android/support/v4/app/FragmentController.java[Added - diff]
• v4/java/android/support/v4/app/FragmentHostCallbacks.java[Added - diff]
• v4/java/android/support/v4/app/FragmentManager.java[diff]
• v4/java/android/support/v4/app/LoaderManager.java[diff]