#80 Provide lazy client connections

[Christian Ohr]

Add a possibility to create lazy client connections, i.e. the (physical) connection is opened only right before the Initiator sends the first message.
This would help for testing purposes as well for read-world problems when the server side is not listening when a connection is established.

[Christian Ohr]

HapiContext.newLazyClient and ConnectionHub.attachLazily
Existing methods connect eagerly.