New tests added, to verify playlist behaviour.
Removed unnecessary dependency from playlistService.
Added few new testes - to test PlayerService functionalities.
Changes needed to introduce playlist item selection.
Minor improvements to previous commit.
Added volume icon to volume control.
Also some minor changes in css file - changes cursors on playback progress control.
Added new method which allow to merge two playlists.
Also changed "add" method name to "addItem".

Updated playlist spec with one more test to verify playlist behaviour.
Changes in youtube playlist loader. Now it is possible to create playlist containing all items from youtube.
Fixed minor issue with volume control.
Now volume icon has width set to 100%.