Default install stanzas.

[pjf]

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.

[AlexanderDzhoganov]

Amazing work, merging now :)