Add new functionality, documentation and move to Rake for building.

New Functionality
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* Add PostgreSQL and Hadoop2 interns.
* Add Octave, GNUplot and Bayesian packages in Sage.
* Add Apache Hive to Hadoop intern.

Documentation
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* Move usage examples to new folder,
* Rework documentation to be developer focused. Should be more technical that
  `skel` documentation for users.

Internals
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* Automate intern building with Rake.
* Add some tests to make sure interns are built correctly.
* Add VM names in VirtualBox console for convenience.
* Numerous puppet tweaks.