Added '%' before snapshot variable

In function create_snapshot for cinder volume, '%' was missed
before variable snapshot from message defination. It was causing
an error during translation of debug message. Included '%'
for getting proper debug log.

Fixes: bug #1183736
Change-Id: I894639a4e5a69be80f4f53ec9d4f9f8648870173

cinder/volume/drivers/emc/emc_smis_common.py

@@ -522,7 +522,7 @@ def create_snapshot(self, snapshot):
         if rc != 0L:
             rc, errordesc = self._wait_for_job_complete(job)
             if rc != 0L:
-                exception_message = (_('Error Create Snapshot: (snapshot)s '
+                exception_message = (_('Error Create Snapshot: %(snapshot)s '
                                      'Volume: %(volume)s Error: %(errordesc)s')
                                      % {'snapshot': snapshotname, 'volume':
                                         volumename, 'errordesc': errordesc})