WIP classic paxos

Thing compiles, passes dialyzer and xref.
Rewrite proposer to gen_server
One election test

And a few fixes
Fix proposer: refresh state on done

When proposer broadcasts majority, clean its state.
Show pid in debug output
Bugfix in increasing numbers
Do not refresh proposer state on new proposal
More crazy tests
Change PAXOS_MOD to more readable value
Fix acceptor not to remake state too often
Bugfix in acceptor

After acceptor gets the value from majority, it is allowed to exit after
executing the imaginary callback.