Add custom zeroclient that supports etherscan (still not working)

The Etherscan Subprovider is not providing some methods we need, such as `eth_getCode`. I'll probably be enhancing it after lunch.

app/scripts/background.js

@@ -6,8 +6,7 @@ const combineStreams = require('pumpify')
 const extend = require('xtend')
 const EthStore = require('eth-store')
 const PortStream = require('./lib/port-stream.js')
-const MetaMaskProvider = require('web3-provider-engine/zero.js')
-const EtherscanProvider = require('web3-provider-engine/subproviders/etherscan')
+const MetaMaskProvider = require('./lib/zero.js')
 const IdentityStore = require('./lib/idStore')
 const createTxNotification = require('./lib/tx-notification.js')
 const configManager = require('./lib/config-manager-singleton')
@@ -48,16 +47,9 @@ var providerOpts = {
   },
   approveTransaction: addUnconfirmedTx,
   signTransaction: idStore.signTransaction.bind(idStore),
+  etherscan: providerConfig.type === 'etherscan',
 }
-var provider
-switch (providerConfig.type) {
-  case 'rpc':
-    provider = MetaMaskProvider(providerOpts)
-    break
-  case 'etherscan':
-    provider = EtherscanProvider(providerOpts)
-    break
-}
+var provider = MetaMaskProvider(providerOpts)
 
 // log new blocks
 provider.on('block', function(block){

app/scripts/lib/zero.js

@@ -0,0 +1,65 @@
+const ProviderEngine = require('web3-provider-engine/index.js')
+const DefaultFixture = require('web3-provider-engine/subproviders/default-fixture.js')
+const NonceTrackerSubprovider = require('web3-provider-engine/subproviders/nonce-tracker.js')
+const CacheSubprovider = require('web3-provider-engine/subproviders/cache.js')
+const FilterSubprovider = require('web3-provider-engine/subproviders/filters.js')
+const HookedWalletSubprovider = require('web3-provider-engine/subproviders/hooked-wallet.js')
+const RpcSubprovider = require('web3-provider-engine/subproviders/rpc.js')
+const EtherscanSubprovider = require('web3-provider-engine/subproviders/etherscan.js')
+
+
+module.exports = ZeroClientProvider
+
+
+function ZeroClientProvider(opts){
+  opts = opts || {}
+
+  var engine = new ProviderEngine()
+
+  // static
+  var staticSubprovider = new DefaultFixture()
+  engine.addProvider(staticSubprovider)
+
+  // nonce tracker
+  engine.addProvider(new NonceTrackerSubprovider())
+
+  // cache layer
+  var cacheSubprovider = new CacheSubprovider()
+  engine.addProvider(cacheSubprovider)
+
+  // filters
+  var filterSubprovider = new FilterSubprovider()
+  engine.addProvider(filterSubprovider)
+
+  // id mgmt
+  var idmgmtSubprovider = new HookedWalletSubprovider({
+    getAccounts: opts.getAccounts,
+    approveTransaction: opts.approveTransaction,
+    signTransaction: opts.signTransaction,
+  })
+  engine.addProvider(idmgmtSubprovider)
+
+  // data source
+  var dataProvider
+  if (!opts.etherscan) {
+    dataProvider = new RpcSubprovider({
+      rpcUrl: opts.rpcUrl || 'https://testrpc.metamask.io/',
+    })
+  } else {
+    dataProvider = new EtherscanSubprovider()
+  }
+  engine.addProvider(dataProvider)
+
+  // // log new blocks
+  // engine.on('block', function(block){
+  //   console.log('================================')
+  //   console.log('BLOCK CHANGED:', '#'+block.number.toString('hex'), '0x'+block.hash.toString('hex'))
+  //   console.log('================================')
+  // })
+
+  // start polling
+  engine.start()
+
+  return engine
+
+}