Some OctetString IEs should accept binary

[wmnsk]

Some of the IE fields that are defined as OctetString type should perhaps accept []byte or something instead of string in their constructors, as they expect more complicated contents than just a string (and most of which are defined in another specification 😡).

e.g., PortManagementInformationContainer, BridgeManagementInformationContainer

This is just a reminder issue, to be considered some time later (hopefully).