Song approval command

[qaisjp]

when a song is approved it is excluded from all automatic skips

• !approve @user %d - allows all songs by the user for %d plays (skips approval check)
• !deapprove @user - reverts the above change
• !approve @user - approves the song "@user" has in the front of his queue for one play
• !approve perm...- whitelists the current song permanently (e.g, in the case of length issues)

To approve a song that would be automatically skipped you need to first approve the user's song (to allow it to play), and then approve the current song permanently.