- getDeviceRate should return bignumber
- test with l-m

backwards compatibility:

- new l-m must be backwards compatible with old l-s

- clean up db stuff satoshis/cryptoAtoms
- clean up other stuff

- add 'ETH' to config in ssu crypto: config.exchanges.settings.coins

[2016-04-06T19:58:17.827Z] ERROR: lamassu-server/39374 on MacBook-Pro: null value in column "satoshis" violates not-null constraint
    error: null value in column "satoshis" violates not-null constraint
        at Connection.parseE (/Users/josh/projects/lamassu-server/node_modules/pg/lib/connection.js:539:11)
        at Connection.parseMessage (/Users/josh/projects/lamassu-server/node_modules/pg/lib/connection.js:366:17)
        at Socket.<anonymous> (/Users/josh/projects/lamassu-server/node_modules/pg/lib/connection.js:105:22)
        at Socket.emit (events.js:95:17)
        at Socket.<anonymous> (_stream_readable.js:765:14)
        at Socket.emit (events.js:92:17)
        at emitReadable_ (_stream_readable.js:427:10)
        at emitReadable (_stream_readable.js:423:5)
        at readableAddChunk (_stream_readable.js:166:9)
        at Socket.Readable.push (_stream_readable.js:128:10)

alter table transactions alter satoshis TYPE bigint;
alter table transactions add crypto_code text default 'BTC';
alter table pending_transactions add crypto_code text default 'BTC';
alter table pending_transactions alter satoshis TYPE bigint;
alter table bills add crypto_code text default 'BTC';
alter table bills alter satoshis TYPE bigint;

- handle geth send failure better
- remove debug
- implement coin selection screen
- ask neal to work on config scripts

[2016-04-17T22:10:57.917Z] ERROR: lamassu-server/32185 on MacBook-Pro.local: could not unlock signer account
    Error: could not unlock signer account
        at Object.module.exports.InvalidResponse (/Users/josh/projects/lamassu-geth/node_modules/web3/lib/web3/errors.js:35:16)
        at /Users/josh/projects/lamassu-geth/node_modules/web3/lib/web3/requestmanager.js:86:36
        at request.onreadystatechange (/Users/josh/projects/lamassu-geth/node_modules/web3/lib/web3/httpprovider.js:114:13)
        at dispatchEvent (/Users/josh/projects/lamassu-geth/node_modules/web3/node_modules/xmlhttprequest/lib/XMLHttpRequest.js:591:25)
        at setState (/Users/josh/projects/lamassu-geth/node_modules/web3/node_modules/xmlhttprequest/lib/XMLHttpRequest.js:610:14)
        at IncomingMessage.<anonymous> (/Users/josh/projects/lamassu-geth/node_modules/web3/node_modules/xmlhttprequest/lib/XMLHttpRequest.js:447:13)
        at emitNone (events.js:72:20)
        at IncomingMessage.emit (events.js:166:7)
        at endReadableNT (_stream_readable.js:913:12)
        at nextTickCallbackWith2Args (node.js:442:9)
/Users/josh/projects/lamassu-server/lib/postgresql_interface.js:301
    satoshis.toString(),
            ^
better handling of this error