Update Ruby-Build definition in OSX

$ rbenv install 2.1.3

ruby-build: definition not found: 2.1.3

You can list all available versions with `rbenv install --list'.

If the version you're looking for is not present, first try upgrading

ruby-build. If it's still missing, open a request on the ruby-build

issue tracker: https://github.com/sstephenson/ruby-build/issues

$ sudo brew uninstall ruby-build

Uninstalling /usr/local/Cellar/ruby-build/20140702...

$ sudo brew install --HEAD ruby-build

==> Cloning https://github.com/sstephenson/ruby-build.git

Cloning into '/Library/Caches/Homebrew/ruby-build--git'...

remote: Counting objects: 343, done.

remote: Compressing objects: 100% (276/276), done.

remote: Total 343 (delta 147), reused 154 (delta 63), pack-reused 0

Receiving objects: 100% (343/343), 88.76 KiB | 126.00 KiB/s, done.

Resolving deltas: 100% (147/147), done.

Checking connectivity... done.

==> ./install.sh

$ rbenv install 2.1.3

Downloading ruby-2.1.3.tar.bz2...

-> https://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.3.tar.bz2