Upgrades rubygems for 1.9.1: 1.3.5 -> 1.3.7
Update share/ruby-build/rbx-2.0.0-dev

Rbx 2.0.0-dev need yaml install like rbx 2.0.0-rc1
ruby-build 20130118
Support selection of 'make' tool via environment variable
Merge pull request #272 from onibox/make-env-var

Support selection of 'make' tool via environment variable
Merge pull request #271 from nobu/master

No needs to chmod all directories.
Update examples
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 for Ruby 2.0 on OS X.

Apple ships a patched, incompatible OpenSSL. We build a compatible
OpenSSL from source.
Add PACKAGE_{CONFIGURE,MAKE}_OPTS_ARRAY for injecting quoted arguments
Extract `package_option` helper
Default CC=cc for broken Ruby 2.0 gcc detection on OS X
Quote `$PREFIX_PATH`