* Adding output stats from plugin, when available
* adding grin config
* moving pow crate from core/pow to it's own crate
* moving POW/mining stuff into pow module, and removing mining dependency from chain
* refactored most of mining into pow module...miner.rs still in server
* update grin tests
* updating genesis block mining to use configured miner, if available
* chain tests back into chain, done with pow refactor
* use tag of cuckoo-miner for pr