[#42296389] Copy of ruby1.9.2 for rbenv 1.9.3

Copy the manifests for ruby1.9.2 as a starting point for our new
rbenv-ruby-1.9.3-p392 package.
[#42296389] Initial manifests for rbenv-ruby-1.9.3

Installs Ruby to a prefix directory. The parent of which is owned by the
rbenv package, which is listed as a dependency.

Package name contains the entire version string so that we can have multiple
unique versions (e.g. 1.9.2-p290, 1.9.2-p320, 1.9.3-p392) in the same repo.

This version of Ruby ships with rubygems 1.8.23 and thus doesn't need an
updated version.
[#42296389] Build ruby 1.9.3 against libyaml-dev

Added as a build dependency so that autoconf picks it up from inside the
chroot. This will fix psych and the warning:

    /usr/lib/rbenv/versions/1.9.3-p392/lib/ruby/1.9.1/yaml.rb:56:in `<top (required)>':
    It seems your ruby installation is missing psych (for YAML output).
    To eliminate this warning, please install libyaml and reinstall your ruby.
Merge pull request #1 from alphagov/42296389-rbenv-ruby-193

[#42296389] Adding package sources for rbenv-ruby-1.9.3 for precise