MB-100: killed support of never used http COPY method

Change-Id: I9fa7ab6f16e989f924e72eb9e88ba87e16f10756
Reviewed-on: http://review.couchbase.org/28250
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Pavel Blagodov <stochmail@gmail.com>