Allow applications to configure initial policy

[GoogleCodeExporter]

Right now, we applications using the licensing library default to 0 grace 
period runs until they contact the server and obtain a valid license.

It would be useful for some developers to allow a non-0 initial grace period. 
We should expose a knob for this.

The only caveat is that a user could reset the grace period by deleting their 
application data. For some applications this may be an acceptable trade-off, 
but it should be clearly documented. (The default should probably remain 0.)

Further, the library should notice if the policy SharedPreferences does not 
exist and delete the rest of the application data in that case.

Original issue reported on code.google.com by trevorjohns@google.com on 29 Jul 2010 at 12:11

[GoogleCodeExporter]

We need to be careful about the case where a user upgrades an app from a 
version that didn't do license-checking to a version that does. Then the grace 
period policy could delete a valid user's data on first launch of the upgrade 
if the user happens to not have network connectivity at the time.

Original comment by dev...@google.com on 2 Aug 2010 at 11:08