first try at a ry formula
update to v0.4.1, and add a note about ry fullpath
use v0.4.2 and add a v
use HOMEBREW_PREFIX (i.e. /usr/local) for install
add a sha1
slim down the caveats
use double-quotes
use separate arguments for system calls
make ruby-build a recommended dependency
add a `head` link
ry: add 0.4.2 bottle.