Fixing issue #136: Removing an unused constant
Refactoring and fixing a couple of issues:

#134: Refactor AcquireTokenForMSAHandler code in to another class.
#136: The ActorToken JWT constant doesn't appear to be used any where?
Enabling sync method for UserAssertion + clientId flow
Exposing ServiceErrorCodes in AuthenticationResult
Merge pull request #140 from AzureAD/refactoring

Refactoring and addressing a few issues