Add .gitreview for gerrit-review and git-review scripts.

Change-Id: I6b4ab17f484784d3e34c60de0e57cdf321134918
Reviewed-on: http://review.couchbase.org/24510
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Reviewed-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Tested-by: Matt Ingenthron <matt@couchbase.com>