Update requirements-dev to use v15 for osm-common and osm-im

Change-Id: I5bee6844a95b02aed4f5af332e9e1e3d212ac6a5
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/requirements-dev.in b/requirements-dev.in
index 279709a..0ce5c0d 100644
--- a/requirements-dev.in
+++ b/requirements-dev.in
@@ -12,5 +12,5 @@
 #     See the License for the specific language governing permissions and
 #     limitations under the License.
 
-git+https://osm.etsi.org/gerrit/osm/common.git@master#egg=osm-common
--r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=master
+git+https://osm.etsi.org/gerrit/osm/common.git@v15.0#egg=osm-common
+-r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v15.0