[Reviewer: Andy] Create a socket factory daemon

Andy, please can you review this code to introduce a new daemon process that creates sockets in the default namespace and passed them to clients over a named socket. 

This consists of the following pieces:

* The daemon code. 
* An upstart job to start and respawn the daemon. 
* An example client to test the daemon. 
* Code to build a new `clearwater-socket-factory` package as part of building `clearwater-infrastructure`

I have tested this as follows:

* Install the new package, check daemon is running. 
* Kill the daemon, it restarts immediately. 
* Run `sudo stop clearwater-socket-factory`. The daemon stops promptly. Run `sudo start clearwater-socket-factory` and it starts again. 
* Use the test program to connect to a server that is listening with netcat.
* Try to connect to a server that is not listening. This fails after a timeout. 
* Try to connect to a bad hostname (not resolvable in DNS). This fails promptly. 
I will add a comment, and mention this in the `.md` file I'm writing. 

I don't think the following code does work for AAAA records actually, as we pass `AF_INET` as a hint to `getaddrinfo`.