Add custom couchstore target to toy-sriram.xml

Change-Id: If587a1384cee8d59ae82f997f1937e962400b1e2
Reviewed-on: http://review.couchbase.org/41151
Reviewed-by: Sriram Ganesan <sriram@couchbase.com>
Tested-by: Sriram Ganesan <sriram@couchbase.com>