Remove the ability to specify a custom directory for mediawiki
It doesn't actually work because the timer jobs assums they can
infer the directory from the site name.
- [DH] cookbooks/foundation/recipes/board.rb
- [DH] cookbooks/foundation/recipes/dwg.rb
- [DH] cookbooks/foundation/recipes/mwg.rb
- [DH] cookbooks/foundation/recipes/wiki.rb