Merge pull request #184 from emavro/feature-appstore-server

Fixed loading icon issue
Merge branch 'feature-appstore-server' of https://github.com/joomla-projects/joomla-cms into feature-appstore-server
Merge pull request #186 from emavro/feature-appstore-server

Collection of minor fixes
Merge branch 'feature-appstore-server' of https://github.com/joomla-projects/joomla-cms into feature-appstore-server
CSS + JS files unified, category regression fixed