End to bridge encryption implementation

So far this is passing my basic tests, but could use some testing from people
that are much more familiar with how this is supposed to work.

Refs #27

bridge/user.go

@@ -32,6 +32,9 @@ type User struct {
 	bridge *Bridge
 	log    log.Logger
 
+	// TODO finish implementing
+	Admin bool
+
 	guilds     map[string]*database.Guild
 	guildsLock sync.Mutex