* Adding ability to load multiple mining plugins in parallel via cuckoo miner
* updating with newest cuckoo-miner changes
* revert default config value
* update pow document with link to podcast
* workaround the "commitment is not a public key" problem by using to_two_keys() from rust-secp256k1-zkp
* remove secp256k1zkp, update the various Cargo.toml to use rust-secp256k1-zkp from external git repo, update code to not rely on to_pubkey (and use verify_from_commit)
* secp256k1zkp from git
* cleanup secp256k1 dependencies
* gitignore node1 and node2 dirs
* 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
