Add default implementation of GetParameters using Protocol
Add default implementation of GetParameters using Protocol

Connection managers that don't support Protocol have to override the method (should already be the case in actual CMs)

detrout/telepathy-python,max-posedon/telepathy-python,freedesktop-unofficial-mirror/telepathy__telepathy-python,max-posedon/telepathy-python,freedesktop-unofficial-mirror/telepathy__telepathy-python,detrout/telepathy-python