Remove reflective lifecycle methods.
Basic implementation of ShadowPopupMenu

- ability to retrieve most recently shown PopupMenu
- ability to get PopupMenu.OnMenuItemClickListener
- ability to ask if menu is currently showing
Merge pull request #858 from erd/cleanup-shadows

Remove reflective lifecycle methods in favor of ActivityController.
Merge pull request #859 from pivotal-odell/master

Basic implementation of ShadowPopupMenu