[packagekit] crash because of missing store values

[Scott Reeves]

pk_transaction_finished_cb was making calls such that threaded backends would crash referencing NULL because of missing PkStore values.  I just pushed a fix to set the values in pk-refresh when it makes direct calls to the backend.

git commit id - e08688008eac565766ae0828d3fdd1624302ef10

I'm a little concerned about this though because this makes 2 places that need to be changed if those method signatures ever change.