fix(client): use present tense when rolling back

Author: Matthew Fisher

client/deis.py

@@ -1526,7 +1526,7 @@ def releases_rollback(self, args):
         else:
             body = {}
         url = "/api/apps/{app}/releases/rollback".format(**locals())
-        sys.stdout.write('Rollback to v{version}... '.format(**locals()))
+        sys.stdout.write('Rolling back to v{version}... '.format(**locals()))
         sys.stdout.flush()
         try:
             progress = TextProgress()