Added Patch coverage tool

Added Patch coverage tool

After building and running automated tests, you can test
the coverage of your current patch (either in the working
directory, or the head patch, or some other difference to HEAD
supplied by the arguments).

The script will return 1 if the test coverage is less
than 90%, otherwise it will return 0 to indicate no error.

This script will also be run as part of the verification process.

Change-Id: I93b1115014e5383a33977e1950350a41d66e950b
Signed-off-by: David Steele <david.steele@samsung.com>