Mms: Update template activity to Google UI guidelines

Replace floating context menu by contextual action mode.
See http://developer.android.com/guide/topics/ui/menus.html#context-menu

Patch Set 1:    * initial commit

Patch Set 2:    * add forgotten files

Patch Set 3:    * fix some styling issues
                * use correct copyright
                * remove res/menu/templates_list_context_menu.xml

Patch Set 4:    * rebased

Patch Set 5:    * some code cleanup

Patch Set 6:    * move strings to cm_strings.xml

Change-Id: I80bed09427e208ab180b0e7cb3aa1a070507621c