Basic, debugged, Paxos implementation

This does not implement MultiPaxos, preferring to do each round
individually.  It's super-inefficient!
rename message to all-caps, better words
split cluster up into a sequence of developing files
ignore .pyc
Merge pull request #4 from djmitche/introduce-cluster

Introduce cluster
Add me to the README
Merge pull request #3 from djmitche/gitignore-pyc

ignore .pyc
Merge pull request #6 from djmitche/add-me-to-readme

Add me ot the README
First operational version

compile:
  ./rebar compile

run:
  erl -pa ebin
  1> torrent_file:download("../path/to.torrent")
Add Info argument to encode/decode packet
Updating README with a clearer mission statement
Use sets of integers rather than bit sets everywhere
Fix bug when download complete
Handle (and ignore) "extended" messages
Simplify code 

Each peer process now does its own connect, rather
than delegating that to a temp process, which leads
to a complicated hand-off procedure.

Also:

 - start block downloading at a random block, so
   that when downloading the same piece from two
   peers, one will "catch up" with the other, and
   complete faster.
 - keep track of interest/choke, so send/2 does
   not need to ignore messages with no effect.
Use gproc to simplify some code
Add me to README too
Merge pull request #8 from audreyt/patch-1

Add me to README too
Merge pull request #7 from gvwilson/master

Updating README with a clearer mission statement
Adding guidelines re: early and subsequent PRs.