RecyclerView in LayoutLib: better XML attrs.

 - RecyclerView now supports XML attributes natively. Thus, remove the
   custom support via tools attribute. Users with older versions of
   RecyclerView should update.
 - Add Context.getPackageName() support used by RecyclerView.
 - Update SessionParamsFlags with the new changes and rename it to
   RenderParamsFlags.

The attribute behaves slightly different from the original tools
attribute. For usage, see commit 044b5b61e96 in frameworks/support.

Change-Id: I12073e37a2ba411558ca1d3e30c399e3d9a0b144