Modify save playlist to automaticall overwrite

Issue #10, #11 and #12 describe the issue and fix for updating/saving a playlist that already exists. It appears that this was fixed, in 7d064482ba4379555cc6a068e4846f3e70269c96. However when I cloned, this commit seemed to be nowhere in the history. And HEAD was missing the line to remove the playlist before saving it. So I added it. I compiled and tested and it lets me overwrite playlists with saving.

Hope this helps, apologies if I've misunderstood something.