Add support for full radio option

Occasionally we need to include full radio image in incremental OTAs.
Adding --full_radio option to support that.

It needs matching changes in the releasetools.py in the target_files
zip, which comes from device/<vendor>/<device>/releasetools.py.

Bug: 19994922
Change-Id: Id1fb3a9cdb7e67dd9dbadd8fb6cd5fccd358820e