test: use m74 image in public domain

- from Hubble Site hs-2007-41-a-web.jpg
- http://hubblesite.org/gallery/wallpaper/pr2007041a/
rebar: working app skeleton
datagram: unpack binary into orddict
message: unpack most message formats
peer: add start/stop for peer around UDP loop

- should be async in future
options: parse most options to erlang native terms
paperwork: add app.config for logging, alerts, etc
tests: add helper functions to emulate udp messages
merkle: lazy hash algorithm using ordered sets
swerl -> swirl
README and a working Makefile for non-Erlangers
peer: use async datagram parsing & handling
tests: add raw packet & datagram
whitespace: vim reindent all
helper: list comprehension for binary_to_hex

Trivial example from https://github.com/tonyg/erlang-nacl/blob/master/src/nacl.erl#L77
options: improve variable names
message: add empty handler
rebar: new shiny OTP release
debug: clean up unnecessary macros, sort out misc whitespace
tests: add unpack_datagram/0