Squashed commit of the following:

commit 882ba3db77420931d429b5d204f9e2e7b4cf3377
Author: Steve Meyfroidt <steve.meyfroidt@gmail.com>
Date:   Mon Jul 22 17:47:35 2013 +0100

    Remove zombie unicorn.sock

commit 1c008033bf39b6ad401ebe30e0730f0a5993b510
Author: Steve Meyfroidt <steve.meyfroidt@gmail.com>
Date:   Mon Jul 22 17:38:26 2013 +0100

    Write the unicorn pid file into /tmp

commit c7d339e3bef47bb482dde1df1e6f6d345a209bb4
Author: Steve Meyfroidt <steve.meyfroidt@gmail.com>
Date:   Mon Jul 22 14:57:37 2013 +0100

    Remove more string substitution shenanigans

commit 6562b8a29b0e87a0fb4bcea7fd0d9a9b7e82a201
Author: Steve Meyfroidt <steve.meyfroidt@gmail.com>
Date:   Mon Jul 22 14:24:10 2013 +0100

    Put in service wrapper that can do a rolling restart/upgrade of unicorn