Add extension-sensitive asset unzipping

Using data structure to put unzipped assets
into the proper destination folders depending
upon the suffix.

Use this feature to properly install a
default profile file in shared_prefs/
Move default preference values

Move default preference values into their own
file. This file will be unzipped from assets/
into shared_prefs/ by the NativeHelper.
Protect against a null serval instance path
Actually remove su from start script