Worker-slave architecture

[sgraf812]

Default to using the current machine as the only worker, but offer benchmark slave functionality in like this:

$ whoami
master
$ feed-gipeda --master=12345     # that's the port

---
$ whoami
slave1
$ feed-gipeda --slave=192.168.0.34:12345

---
$ whoami
slave2
$ feed-gipeda --slave=192.168.0.34:12345

Roadmap:

• [x] Don't use touch as a mutex anymore
• [x] Determine when to call gipeda in the non-sequential model
• [x] Settle for an implementation (currently ZeroMQ + msgpack or YAML? process-distributed)
• [x] Add the console flags