Chain state provider + Currency Routes + Tests

[micahriggan]

Api

Rest api should be generalized like below

router.use('api/:chain/:network/wallet/:walletId/balance', () => {
  let balance = await ChainStateProvider.getBalanceForWallet(chain, network, walletId);
  res.send({balance});
});

Chain State Provider

• Each chain would implement this interface, then the REST api will function for that chain
• Bitcoin based coins can inherit the BTCStateProvider
• Should lower the barrier to adding new coins to the wallet

Tests

Still have a lot of work left to do here but partial coverage for the following

• Coverage for address endpoints
• Coverage for block endpoints
• Coverage for transaction endpoints