Support for Display Names

[naomi-lgbt]

The global_name property of the user object from Discord represents the user's display name. It would be nice if there was a configuration option to use this instead of the username.

[DarkView]

Unfortunately the version of eris that this bot uses is so antequated that it has no concept of the "new" username changes.
@Dragory will work on a new version with support for this at some point.