Shuffle around command permissions.

 - Commands no longer keep track of permissions.
 - Asakura.Permissions provides a wrapsCmd function.
Move Yukibot.Plugins.Blacklist to Asakura.

This is more of a utility thing than a yukibot-specific plugin, so
it's been moved. `wrapsCmd` has also been modified to work on
CommandDefs, to be consistent with Permissions.
Remove the non-CommandDef variants of register{Long,}Command
Add missing blacklist state module
Store command verbs in the CommandDef