Consensus message buffering and more (#114)

* CLI options and keystore integration

* Replace multiqueue with future::mpsc

* BFT gossip

* Revert to app_dirs

* generate_from_seed commented

* Refactor event loop

* Start consensus by timer

* Message buffering

* Minor fixes

* Work around duty-roster issue.

* some more minor fixes

* fix compilation

* more consistent formatting

* make bft input stream never conclude

* Minor fixes

* add timestamp module to executive

* more cleanups and logging

* Fixed message propagation