Make song availability skipper

[txomon]

This feature should be something that can be enabled/disabled, and that should work taking into account the countries of the currently listening registered users. It should work as follows:

When enabled:

• The user should be warned on the general chat about this song removal reason, and then
• The song should be removed when it reaches the queue

When disabled:

• The song should be warned as not available in the countries that matter to all MoS