Set icon in left file observer manager panel.
Make namerepresenting of file as "artist | song".
Remove files on clean target with force flag.
Add method to get full name of observer.
Show path of current directory in file manager panel.
Handle callback when row of file manager is activated.
Add handler of changing directory on tests.
Update test after chaning return file representing.
Make correct notifying of changing observer.
Return shared_ptr instead of its reference on getting media items.
Implement method to execute action on folder from file manager.

Add stub on executing action on media file.
Reset content of file manager when observer is changed.
Merge branch 'provide-observing-down-in-file-panel'