Import/Export of yaml structure

[h4llow3En]

• The folder structure of yaml playlists needs to be imported into the database (on startup)
• If Playlist exists it will be updated
• also there should be a filewatcher on it so the files can get updated on the filesystem
• Playlist creation via rest api is also possible so we have to write back any changes to the filesystem/yaml structure

[h4llow3En]

@MarauderXtreme Any other ideas on this topic?

[MarauderXtreme]

Sounds good so far.
As mentioned in #24 there needs to be a way to sub-categorise playlists for videogame radiostations.

Since currently images for any given playlist are imported into the database and we want to allow playlist creation via API there should be a way to dump them too.

[h4llow3En]

The images are dumped when the Playlist ist dumped on shutdown.