[Feature Suggestion] No Fee on User Side with Whitelisted UIA

If a UIA issuer has authority to allow or deny users with whitelisting, a possibility of spam attack can be significantly reduced and easily controlled out. In this case, a UIA issuer may want to remove transaction fees from users to facilitate UIA usage, while the issuer pays the fee through the fee pool.

There is a potential customer in Korea(a local government) and if this feature is implemented, we are going to push it more.

Note: The original issuance is [here](https://github.com/cryptonomex/graphene/issues/667)