CBLT-255:  copy all files in SRC/release directory to SRC before building

Change-Id: I224c8f925f96713ae7b2fdd8f245e9a364f7d814
Reviewed-on: http://review.couchbase.org/39746
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>