This adds an Application subclass to get the onCreate() method, which is
called once at the first start up of the app, before any Activity starts.
Tor is configured there to ensure it is setup before anything happens.
This also moves the "Use Tor" pref listener to a more appropriate place.
On all of the devices that I've checked, there is a folder called "Movies"
on the SD Card by default. NewPipe should use that standard location
since it is always downloading movies :). People can always change that
via the preferences.
Also, this makes the defaults the same when creating the dir and when
setting the destination URL.
