dcap: Rename dcap.mover.overwrite to dcap.authz.mover-queue-overwrite and change to boolean property

We use true/false for all boolean properties and this property
should be no exception.

Target: trunk
Require-notes: yes
Require-book: yes
Acked-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Patch: http://rb.dcache.org/r/5865/