* Change NodeCallbacks to Future[Unit] s
* Fix compile issue
* Change try to future
* Change Future.sucessful(()) to FutureUtil.unit
* Callback failure handling, callback docs
* Create functions for executing callbacks, make merkleblock a future
* Convert MerkleBuffersTest to BitcoinSAsyncTest
* Fix compiler errors
* Reorder UpdateBloomFilter tests so that txFromWalletP is a success for both calls and the other test does not wait on the promise to complete