[WIP] (Start of) Rewrite of chef to work properly with CentOS, use rbenv...

.../ruby-build, support multiple runs/upgrades and generally be more resilient.

Known Issues:
* Lots of commented bits and pieces need cleanup
* Foreman export doesn't seem to work amazingly: Will start huginn service properly (i think), but unicorn processes are left running when we stop it?
* Still using 'old method' for sudoers (Chef sudo cookbook doesn't seem to want to work :S)
* Sensitive env variables are shown in `ps aux` for foreman tasks

TODO:
* Make more bits configurable (see attributes/default.rb)
* Continue adding support for setting .env configuration from chef role
* Fix foreman/unicorn issues
* Cleanup/remove huginn_development cookbook and modify it to work from just the huginn_development role
* Test a fresh install on a clean/new server (For CentOS AND other platforms)
* Add support for SSH keys instead of default password (and lock huginn account password)
* Etc

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This sounds relevant to the foreman/unicorn type issue, but not 100%;
* http://stackoverflow.com/questions/8667425/using-upstart-to-manage-unicorn-w-rbenv-bundler-binstubs-w-ruby-local-exec-s
* https://gist.github.com/kesor/6255584
* http://superuser.com/questions/213416/running-upstart-jobs-as-unprivileged-users
  * http://upstart.ubuntu.com/cookbook/#run-a-job-as-a-different-user

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I probably won't have a heap of time to hack on this over the next week or so, but if anyone can help out (i feel like this particular issue is getting way over my head), particularly with the foreman/unicorn type issues then that would be epic!

More than happy to answer questions/try to explain what i've done where/why :p

@albertsun @cantino @dsander @mfclarke @opyate @rudimk @snicker etc