Add default value to wait parameter

Adding the wait param without a default broke the api for things calling
it the old way.

Change-Id: I75bbec19f06a0f85bc9cb1fbe4d4c6560dadba49

shade/task_manager.py

@@ -72,7 +72,7 @@ class Task(object):
         self._traceback = tb
         self._finished.set()
 
-    def wait(self, raw):
+    def wait(self, raw=False):
         self._finished.wait()
 
         if self._exception: