CBLT-42:  organize WORKSPACE, fix "sync_gateway/build" path error

Change-Id: I0aa9a9f84aea1d0cf26f144e8f8dd0b39c23c9e6
Reviewed-on: http://review.couchbase.org/37208
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>