Allow plugins to run code before and after the installation process
`rbenv install` with no arguments defaults to `rbenv local`
Confirm reinstalling already-installed versions unless invoked with --force
Move MAKE default near the others
Ensure $MAKE is quoted
Document $MAKE
ruby-build 20130129
Add support for `RUBY_CONFIGURE_OPTS` and `RUBY_MAKE_OPTS`

These variables let you pass Ruby-specific configure and make options
that will not be passed to dependent packages like libyaml.
Build OpenSSL so Ruby 2.0 installs Just Work on Mountain Lion.

Ruby 2.0 won't compile the OpenSSL extension on Mountain Lion
because Apple shipped a crippled OpenSSL distribution. The fix
is to build your own OpenSSL and link to that instead:

  brew install openssl
  CONFIGURE_OPTS="--with-openssl-dir=`brew --prefix openssl`" \
    rbenv install 2.0.0-rc1

That's a lot of hassle for what will soon be a very common case.
We can fix it by bundling a working OpenSSL.