Rewrite policy to use the new changes of common policy

The oslo has rewritten the common policy for a long time, using a
Enforer class to replace the old check function. In order to sync the
common policy, We have to also changed the tuskar policy and
related unittests.
Sync policy and relate module from Oslo.
   Some related change-id:Ife909bdf3277ef33c2fb1eae16ae261fa6374c63
                change-id:Ife84189be4b86a3ee90da4539ff2dbed125be23d
Closes-Bug: #1288178

Change-Id: Ie4d8d31031d44ce46788d00624740825c04c7e88
Merge "Rewrite policy to use the new changes of common policy"