use rspec instead of test::unit
fix fallout from project rename

healthcheck is already in rubygems, so i renamed to app_status.
more cleanup from test::unit -> rspec
app_status not healthcheck, again
tests!
usability improvements

  - use HashWithIndifferentAccess since symbols or strings seem more natural
    in varying contexts.
  - improve error messages for add() calls.
details are now called checks
move nagios check so its easier to find

keeping bin/ dir around for bundler/rvm binstubs
add 'what is this?' information