implement and enable sorting in the views
Summary:
implements the option to sort ascending or descending for all views except the album view.
currently there is only one possibility to sort for each view, e.g. album name for the all album view
Reviewers: Elisa, mgallien
Reviewed By: Elisa, mgallien
Subscribers: mgallien, ngraham
Tags: Elisa
Differential Revision: https://phabricator.kde.org/D12317