Add jruby-1.7.20

add rbx-2.5.3

Add jruby-9.0.0.0.pre2

The checksum of the official download has changed since initial publish
time. I have compared the two downloads and it seems it was only a
single whitespace change in `.bundle/config`.

Add 'cd -' to proposed steps to upgrade ruby-build

When a target is not found, rbenv-install proposes pulling changes from
upstream. This involves changing the directory to the ruby-build checkout.

This patch adds a '&& cd -' to change the working directory back to where
we've been. Should work on at least Bash and Zsh.

Add 2.2.2, 2.1.6 and 2.0.0-p645 but they work

See https://github.com/sstephenson/ruby-build/pull/733 to get the joke.

Upgrade openssl-1.0.1m

added definition of Ruby 2.2.1

Rename jruby-9.0.0.0-pre1 to jruby-9.0.0.0.pre1

So the installed ruby version will match what is used in `.ruby-version` files

added definition of ruby 2.0.0-p643

removed jruby-9000 definitions

add rbx-2.5.2