Default install stanzas.

These *freakin' rock*. For a typically packaged mod, one can
now use something like this:

    {
        "spec_version"   : 1,
        "identifier"     : "DogeCoinFlag",
        "$kref"          : "#/ckan/kerbalstuff",
    }

We go looking through the zipfile for a directory with the same
identifier as the mod, and install that to GameData.

Tested, working, and comes with unit tests.

Closes #127 like a boss.