fixes #2367 - Ruby 2.0 support

* require bundler 1.3, preventing ruby-debug19 getting installed on Ruby 2
* update 1.9 gems to install on 2.0 too
* don't use empty arrays in Hash constructor, causes ArgumentError

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There's a separate Jenkins job here which tests it with Ruby 2.0.0 and Puppet 3.2.0-rc1:
http://ci.theforeman.org/job/test_develop_pull_request_rb2/

Updating to this version of Puppet also breaks Ruby 1.9.2, see [#2413](http://projects.theforeman.org/issues/2413) and the [foreman-dev thread](http://groups.google.com/group/foreman-dev/browse_thread/thread/ee16102943c6b447) for more info, but the plan is to drop support at least for the meantime.