adding process_name label to logger

- [x] added an identifier field to the loggers, which is logged with every line.  this makes it easier to identify/search log lines when we redirect stdout to a file
- [x] master process sets this field to the provisioner id, which is modified slightly to "master-[hostname]-pid"
- [x] workers set this field to the worker name, which master sets to "worker-[tenant]-[number]"
- [ ] fyi, worker code and master code is still separate, each with their own logger... i want to combine these at some point soon.

sample logs:
```
2014-08-28 15:06:42 -0700 master-dereks-macbook-air.local-56484 INFO: starting heartbeat thread
2014-08-28 15:06:42 -0700 master-dereks-macbook-air.local-56484 INFO: Registering with server at http://localhost:55054/v2/provisioners/dereks-macbook-air.local-56484: {"id":"dereks-macbook-air.local.56484","capacityTotal":"10","host":"127.0.0.1","port":"55056"}
2014-08-28 15:06:42 -0700 master-dereks-macbook-air.local-56484 INFO: started signal processing thread
2014-08-28 15:06:42 -0700 master-dereks-macbook-air.local-56484 INFO: starting resource thread
2014-08-28 15:06:42 -0700 master-dereks-macbook-air.local-56484 INFO: Successfully registered
2014-08-28 15:06:43 -0700 master-dereks-macbook-air.local-56484 INFO: adding/updating tenant id: superadmin
2014-08-28 15:06:46 -0700 worker-superadmin-3 INFO: Starting provisioner with id dereks-macbook-air.local.56504, connecting to server http://localhost:55054
2014-08-28 15:06:46 -0700 worker-superadmin-1 INFO: Starting provisioner with id dereks-macbook-air.local.56502, connecting to server http://localhost:55054
2014-08-28 15:06:46 -0700 worker-superadmin-2 INFO: Starting provisioner with id dereks-macbook-air.local.56503, connecting to server http://localhost:55054
2014-08-28 15:06:46 -0700 worker-superadmin-5 INFO: Starting provisioner with id dereks-macbook-air.local.56506, connecting to server http://localhost:55054
2014-08-28 15:06:46 -0700 worker-superadmin-4 INFO: Starting provisioner with id dereks-macbook-air.local.56505, connecting to server http://localhost:55054
```
I know that this isn't code that you changed, but it showed up in the diff, so... Can we use: `Socket.gethostname.downcase.split('.').first` to only get the short hostname, instead?