Merged upstream changes

BugFix: Now Shift+F3 and F3 search keys (and also Esc) work outside
SearchLineEdit widget.
BugFix: fixed freeze for install orphaned/yaourt package (thanks to
tbinkau).
BugFix: fixed notify-send code in octopi-notifier (thanks to vedgy).
merged upstream change
Refactored the packageView to use a single model.

Imho much better to read and build upon. Also it should be a bit faster.