Fixes and improvements for PoC-1 Testnet (#143)

* Fix initialisations and add a test.

* Fix test.

* Fix overflow bug.

* Minor refactoring and fixes.

* Fix vote threshold.

* Add note.

* Fixes for latest rust and the readme.

* Better readme.

* An extra validator for PoC-1

* Update README.

* PoC-1 bootnodes.

* don't return async::notready for messages without scheduling wakeup

* Fix endowed account

* give polkadot control over round proposer based on random seed

* address grumbles.