Make sure that multiple installs of KA Lite have their own cache location

Title says it all.

Issue:
* Install 2 versions of KA Lite on the same machine, and you can get incorrectly rendered pages, as their cache locations may overlap.

Solution:
* Hash the path of the installation (which uniquely defines it), and include that hash in the cache location.

Testing:
* True test:
    * Install KA Lite, download videos, render (and therefore cache) landing page
    * Install another version of KA Lite.  Start as the same user as the previous, render the landing page.
    * In the past, this would show the page of the other install (with videos available).  now, it does not :)
* Fake test:
    * Just install KA Lite and make sure it works :)