The current pyalpm implementation does not handle proper refcounting
which means the alpm_handle was never freed otherwise accessing an
object when the Handle goes out of scope leads to segfaults.

This means everything needs to keep a reference to the pyalpm Handle
object for every object created from it. The database object now
receives a Handle and increases the refcount for it to stop it from
being removed by the Python garbage collector.

Signed-off-by: Jelle van der Waa <jelle@archlinux.org>