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

config/bridge.go

@@ -30,6 +30,8 @@ type bridge struct {
 	DoublePuppetAllowDiscovery bool              `yaml:"double_puppet_allow_discovery"`
 	LoginSharedSecretMap       map[string]string `yaml:"login_shared_secret_map"`
 
+	Encryption encryption `yaml:"encryption"`
+
 	usernameTemplate    *template.Template `yaml:"-"`
 	displaynameTemplate *template.Template `yaml:"-"`
 	channelnameTemplate *template.Template `yaml:"-"`