build: eunit target should fail if a test fails
swarm: add gen_server supervisor

- manages overall swarm relationship to peers
- ensures linkage between swarm and channels via gproc
worker: stop on swarm_id not root_hash
options: use swarm_id instead of root_hash when binary instead of string data
swarm: remove spec from comments
swirl: expose swarm API to users
swirl: document start/stop_swarm/1 functions
tests: use thorne character c39e / Þ for test hashes
build: add `make dev` for observer or custom options
Merge branch 'refs/heads/feature/add-swarm-supervisor' into develop