Cleanup FloatingActionButton code to remove unneeded code.

Remove code that is no longer needed since minSdk for support library is API 14.
This code collapses FloatingActionButtonImpl, FloatingActionButtonGingerbread
and FloatingActionButtonIcs into one class.

Bug: 32794064
Test: ./gradlew clean assemble still works
Change-Id: Id20c0d1807e08ab11ece63883debe2682cfa815f
7 files changed