Separate Exchange application

* Clean up AndroidManifest, Android.mk, and proguard.flags
* Refactor to use emailcommon
* Remove Email app code/resources (note: this CL starts from the
  single Email application)
* Update Exchange unit tests to use EmailProvider "live" and
  clean up after itself
* All unit tests pass

Bug: 3442973
Change-Id: Iced00ae546dd4ddb9a66e297d3ac2dc2977e20eb
51 files changed