(Sailfish) Fix cover

* fix text alignment
* current index is get from item at the middle of ListView
* do not position at index if "next" CoverAction is not trigger
(Sailfish) Update some file according to the new template
Remove video support

9GAG does not support posting video anymore
Implemented login to 9gag

First step on our way to like/dislike buttons is to be logged in.
Adding ability to like/dislike

- New class VotingManager, handles comms to 9gag
- New params in gagobject/gagmodel
- New settings for username
- New gui for login/logout