* remove receive_coinbase fn from wallet to wallet client
* start moving clients into separate mod
* rustfmt
* move wallet client + start listener into wallet 'clients'
* rustfmt
* refactor API to make it more modular and completely decouple sending
* rustfmt
* further decouple API from sending methods
* rustfmt
* remove wallet to wallet client trait
* rustfmt
* rename / refactor client + adapters
* rustfmt
* add adapter concept
* add midding node_clients dir
* add file and null adapters
* rustfmt
* remove receive from owner api
* factor out receiving slates into trait
* rustfmt
* adding listen trait
* rustfmt
* change listener to use trait
* rustfmt
* add test for file-based exchange
* replace http api send command
* rustfmt
* move controller out of libwallet and into top-level wallet dir
* rustfmt
* add moved controller
* introduce grin_keychain, encapsulate derivation of secret_keys
* core compiles against keychain, tests don't run yet
* core tests are now passing against keychain
* wip - getting wallet working with keychain
* add util and keychain to travis test matrix
* basic test around key derivation
* 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
