go-libp2p & pubsub process implementation

[smartin015]

Iteration on #5 - using golang libp2p and pubsub packages to provide decentralized print queue management.

• [x] Unit tests for golang modules
  • [x] ZMQ command
  • [x] Discovery
  • [x] RAFT
  • [x] Topic receiver
  • [x] Polling
  • [x] Handlers
  • [x] Server events
  • [x] Registry generator
• [x] Remove IPFS code from peerprint golang binary, replace with CLI flags as needed
• [x] Add registry fetching to new wan/registry.py file
• [x] Unit tests for python modules
  • [x] proc.py
  • [x] comms.py
  • [x] ipfs.py
  • [x] registry.py
  • [x] wan_queue.py
  • [x] filesharing.py, IPFSFileshare class
• [x] Add registry generator command to server binary
• [x] Remove user inputs on demo.py and turn it into an integration test (run by travis)
• [x] Unit test changes to raft.go (use of state chan for notifying)
• [x] Update docs/contributing.md with final setup instructions
• [x] Clean up any unused protos
• [x] Set up Travis CI testing of golang unit tests
• [ ] Find and fix race conditions on startup (due to prior dangling sockets?)

Docs cleanup:

• [x] Logo not loading
• [x] Generalize crisis doc point
• [x] "It feels like it's missing a section on how to join a queue"
• [x] Quick shell/command for creating a registry with reasonable defaults