Script for updating kalite from a zip file

This branch depends on package_kalite and clean_settings_paths branches (currently outstanding pull requests).

** WARNING: If you want to test this on a branch with existing movies/data in your database, I highly recommend making a backup, as this code will touch those files (database should be safe, it's only copied; movie files may move, depending on what option you choose!) **

Usage:
python manage.py update # still updates via git
python manage.py update --file=path_to_zip_file # updates via zip

This branch provides a script that updates KA Lite using a zip file.  It essentially:
* Prompts the user for an install location
* Unpacks files to a temp location
* Copies the database to the temp install, and migrates the schema
* Copies over local_settings
* Moves over movie files (only if specified by the user)
* Tests the server (as best it can)
* Moves the new install to the desired final location.

I tested this on MacOS and Windows XP.