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

This is to fix the error when installing new gems that have executables
which match existing binstubs in the Rubinius bin directory:

    "bundle" from bundler conflicts with PREFIX/gems/bin/bundle

RubyGems is supposed to override the binstub if it detects that the
previous one was also generated by RubyGems for the gem of the same
name, but its detection mechanism gets thrown off by having a double
shebang as a result of our binstubs fixing process.

https://github.com/rubygems/rubygems/blob/v2.2.2/lib/rubygems/installer.rb#L149-L154

This avoids generating binstubs with a double shebang.

add rbx-2.5.1