Add object mode stream support to Converter class.

Creating a Converter instance in object mode allows to read and write
Header and HeaderSet instances directly (without having to serialize
and deserialize them using the VBusRecordingConverter).
Add object mode support to VBusRecordingConverter.
Add `adaptTimeout` helper that changes timeouts during Travis test.
Change Recorder to use object mode streams.
Change DLxRecorder to use object mode streams.
Change FileSystemRecorder to use object mode streams.
Change TestRecorder to use object mode streams.