Removes Baloo dependency

Summary: * Application no longer uses Baloo for image fetching

Test Plan: Works fine without Baloo, uses FileSystemImageFetcher that uses Qt's library(QMimeDatabase, QDirIterator) to fetch images

Reviewers: Koko, mart

Reviewed By: Koko, mart

Differential Revision: https://phabricator.kde.org/D6407