GPII-413: Add a Device Reporter plugin based-up on PackageKit

This pull request includes a first device reporter plugin, which uses the packageKit node module.
As a brief explanation, the deviceReporter plugin is being initialized at start-up time and stores all the installed packages in memory, which is used later on in order to provide a quick response.

Currently, and as a demonstration of how it works, [this pull request] includes the bits on the solution registry to use this new functionality.

To try this new feature, you have to start de the GPII in production mode, this is: <pre>NODE_ENV="fm.ps.sr.dr.mm.os.lms.production" node gpii.js</pre>

  [this pull request]: https://github.com/GPII/universal/pull/246
To be clear:  this particular test checks if 'tuxguitar' is installed *or available*.  It won't fail if not installed.

Still, point taken:  there is another test that does depend on tuxguitar not being installed.  There is a comment there advertising that fact (line 48), quoting: 
    // TODO:  This tests that tuxguitar is not installed, but it's not really
    // an error if it's there.  For now, manually remove tuxguitar
    // before running tests.

After discussing with Javi, we will put in checks to see if tuxguitar is there, and run the tests as per the actual initial conditions, and advertise that fact with a message on the console.

A better solution is to have access to a test package that is known to be installed, can be easily installed, removed, etc., and use it to set the initial conditions.