doc: added debug info to FAQ
add: added Help to main menu, with About Dialog & Online docs
translation: rename yum to dnf in strings & rebuild .pot file
doc: added link to translation page at transifex
add: groups are objects, add groups to queue, not packages
refactor: group should be reprecented as python objects in group view, to make
it possible to unselect the group, when remove from the queue view.
add: group view: show group install state as stared/non-started icon
add: added code for installing and removing groups