Manually set networkId

By default kredits-contracts gets the networkId from the web3 object.
This causes some random JSON RPC errors when using MetaMask:
https://github.com/MetaMask/metamask-plugin/issues/1538

This set the default networkId to 17 which is our custom private
network. For development purposes the networkId can also be set
dynamically through the config:networkId local storage entry.

app/services/kredits.js

@@ -52,6 +52,9 @@ export default Service.extend({
     let contract = null;
 
     if (isPresent(config.contractMetadata)) {
+      if (localStorage.getItem('config:networkId')) {
+        config.contractMetadata['networkId'] = localStorage.getItem('config:networkId');
+      }
       contract = kreditsContracts(this.get('web3'), config.contractMetadata)['Kredits'];
     } else {
       contract = kreditsContracts(this.get('web3'))['Kredits'];