Command to add/remove exceptions to the swear filter

[Arlodotexe]

The new swear filter is good, but it catches a lot of things that ought not to get caught because of how broad the Regex is.

There have been instances where a persons name, or legitimate terms have been mistaken by the bot for a swear word, such as ishittestvisible.

Let's add a few new commands to the bot:

• Store new swear filter exceptions
• Remove swear filter exceptions
• List exceptions

The data should be stored in the backend database, and proper models created in the backend.
Only moderators should be able to manage use the add/remove commands.