Remove stock maps from the "Vote"-menu (1.0)

Sometimes its desired to remove maps or campaigns so players can't vote for it. While this is easy for custom content - simply remove the respective files - its more difficult to remove "stock" content.
1. Preamble =========== Sometimes its desired to remove maps or campaigns so players can't vote for it. While this is easy for custom content - simply remove the respective files - its more difficult to remove "stock" content, like the default ma