CBD-946:  add 3.0.0 branch which is really master

Change-Id: Id277ae89810a668fad5f2db5c689b9a3ae222c4f
Reviewed-on: http://review.couchbase.org/26643
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>
CBD-946:  rearrange tokens so that same files appear same

preparation for renaming the files that refer to the master
branch to have the same form as files to refer to branches:

    master.xml             =>  branch-master.xml
    override.xml           =>  override-master.xml
    external-override.xml  =>  external-override-master.xml

Change-Id: I43ab833af0b4676dd0df1a5cc556c4fe8fad51dc
Reviewed-on: http://review.couchbase.org/26644
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>