Changelogs and Statistics updates

Changelogs for SailfishOS.

Warehouse for SailfishOS now shows applications changelogs.
Changelogs for sailfishos packages now can be automatically updated based on info from rpm packages. Dont forget to tick 'autoupdate changelogs' flag!

Download statistics.

Stats core has been updated. Now all downloads stats are updated online! Don't ever miss the moment when your app becomes popular.