Merge pull request #5 from miracle2k/errors

Add http error responses.
Update method signature in server example
Make server example register with proper port syntax.

Before, you needed to specify the port without a colon and the
service was registered in the same way.
Add Procfile, for easy development env setup.
Serve a TLS port alongside unencrypted HTTP.
Add SNI-based HTTPS routing.
Fix spelling in comment.
Support custom service name in client example.

This evolves in more towards a real RPC command line client.
Allow setting domain cert/key via RPC client.
Store TLS keypair per domain in etcd, use for serving.