Add channel manipulation commands

[ScoreUnder]

Allow a user to modify channels they own with commands like:

• &voice name Hangout 2 to change name
• &voice perm locked to turn a channel private
  etc.

I was considering:

1. a command for name changes
2. a command for permission changes
3. a command for uninviting, maybe?

They could all be grouped as subcommands under one bigger &voice command, allowing users who created a voice channel to admin it even if they don't have 2 factor authentication enabled.