Remove parseCommandStream hack

[weissi]

this needs to be implemented

        public mutating func parseCommandStream(buffer: inout ByteBuffer) throws -> NIOIMAP.CommandStream? {
            // TODO: SynchronisingLiteralParser should be added here but currently we don't have a place to return
            // the necessary continuations.

The right return type gives us the following information:

• CommandStream?: a parsed command if enough data
• number of continue requests to send

[Davidde94]

@weissi this has been resolved if I'm not mistaken?

[weissi]

you are not, thank you!