Refactored the packageView to use a single model.

Hi,
i refactored the tvpackages, so that it doesnt use 4 models + proxy, but 1. The idea is to use a central repository (PackageRepository). You can then connect models (PackageModel) to that, which will update automatically if changes are pulled from pacman (or yaourt) to the repo. This means you can use any data available from pacman to filter / update ... your model and dont have to compare pixmaps for status etc pp.

i left out as many changes possible to keep the commit "small". kinda failed, but thats the minimum change i could come up with. atm this should behave exactly as octopi.

i hope you like it. this will enable a few more fixes and potentially some enhancements as well.
Happy Easter...