Use authorize instead of enforce for policies

After fully implementing policies in code, the authorize method
can be safely used and its a safeguard against introducing
policies for some API which are not properly defined in the code.

Change-Id: I499f13c34027b217bf1de905f829f36ef919e3b8

sahara/api/acl.py

@@ -39,8 +39,8 @@ def enforce(rule):
         @functools.wraps(func)
         def handler(*args, **kwargs):
             ctx = context.ctx()
-            ENFORCER.enforce(rule, {}, ctx.to_dict(), do_raise=True,
-                             exc=exceptions.Forbidden)
+            ENFORCER.authorize(rule, {}, ctx.to_dict(), do_raise=True,
+                               exc=exceptions.Forbidden)
 
             return func(*args, **kwargs)
         return handler