Async TTM code cleanup.

* Code cleanup in the Async Token Transform Manager.
  - some code simplications.
  - some dead code removed.
  - some variables / fields renamed.
  - some minor code refactoring.

* Commented out unneeded ayncCB callback in Template Handler.

* No change in parser tests.

* Verified that en:Barack Obama RTs correctly.

Change-Id: I1e534926e455714bebad8238f612bc89aea672f5