Reword deprecation warning for dream.py

- this plus previous commit closes #1087

Author: db3000

scripts/dream.py

@@ -5,6 +5,7 @@
 import invoke
 
 if __name__ == '__main__':
-    warnings.warn("dream.py is deprecated, please run invoke.py instead",
+    warnings.warn("dream.py is being deprecated, please run invoke.py for the "
+                  "new UI/API or legacy_api.py for the old API",
                   DeprecationWarning)
     invoke.main()