Merge branch `accepts` into `master`.
Rename `paxos.js` to `proposer.js`.

See #89.
Upgrade Proof to 0.0.50.

Closes #90.
Complete `proposer.js` rename.

See #89.
Testing leader overrides.
Fixing tests.
Working on leader overrides.
Fix step() call.
Cleanup.
Remove 'multi' parameter.