Finish implementation of Ledger process/Features logic:
* RIPPLE_NO_PROPOSE_FEATURES deactivates ledger features
* Reduce dependence on getApp via dependency injection
* Inject Journal, tidy up classes:
    - Features
    - FeaturesImpl
    - FeeVote
    - FeeVoteImpl

* RIPPLE_NO_PROPOSE_FEATURES deactivates ledger features
* Reduce dependence on getApp via dependency injection
* Complete change process / Features logic