Update UI state on ethStore updates

UI was remarkably not relying on ethStore for updates, so things like account balances were frozen until user activity.

Fixes #963

app/scripts/metamask-controller.js

@@ -60,6 +60,8 @@ module.exports = class MetamaskController {
     this.idStoreMigrator = new IdStoreMigrator({
       configManager: this.configManager,
     })
+
+    this.ethStore.on('update', this.sendUpdate.bind(this))
   }
 
   getState () {