Couchbase::MemoryMappedFile is moved to cb::
Couchbase::MemoryMappedFile is moved to cb::

Change-Id: I4c59c5cbdf7ef39f04a8f12a0c0f789642318eab
Reviewed-on: http://review.couchbase.org/69241
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Daniel Owen <b3fc0e1a51f252986e60be7da121b74d3ac6845f@couchbase.com>

daverigby/kv_engine,couchbase/memcached,daverigby/memcached,couchbase/memcached,daverigby/kv_engine,daverigby/memcached,daverigby/memcached,couchbase/memcached,daverigby/memcached,daverigby/kv_engine,daverigby/kv_engine,couchbase/memcached