Update boxes to use 127.0.0.1 instead of localhost

[bmmpxf]

As per https://consensys.slack.com/messages/C1D2T7NLC/

When offline, TestRPC / Truffle Develop fails with an Invalid JSON RPC response error.

The problem is that localhost needs to be resolved. Switching the network connection string to use 127.0.0.1 instead of localhost removes the need for a network lookup.

We should update our Truffle Boxes to reflect this.