Progress

- Going back to one global transition (sorry but it's the easiest way atm)
- First tries to download all packages, then to install them (the second time will try to re-download all failed packages in the first try)
- Global progress bar not used anymore (@faidoc)
- Local progress bar shows: download process for each package and then total install process
- Changed some strings (sorry, but it had to be done)

The key was moving this line and changing time from 1000 to 100 (tested it before without moving and was a total disaster)

GLib.timeout_add(100, self.manage_events_from_cb_queue)

Please, test it asap and tell me what you think!