AI 144202: am: CL 144137 am: CL 144136 Make calendar widget correctly launch Calendar...

AI 144202: am: CL 144137 am: CL 144136 Make calendar widget correctly launch Calendar app instead of creating a second task stack.
  Fixes the following issues:
  - Calendar widget and calendar icon always launch to a specific calendar view--the view last selected by user.
  - Launching from both widget and app icon clears any existing activity stacks.
  - We correctly keeps the stack history when switching between activities using long-press-home-hardkey
  Original author: jsharkey
  Merged from: //branches/cupcake/...
  Original author: android-build
  Merged from: //branches/donutburger/...

Automated import of CL 144202