Implementation of datatransfer

add the data transfer functionality to LRC

this patch does not fullfil all the models specifications
and is not fully "concern separated" due to design flaws
(much of the datatransfer is delegated to conversation model).
That will be corrected further in time.

Change-Id: I9bc3d3f8fc544fe97ef43805bad54a5779797234
Reviewed-by: Anthony Léonard <anthony.leonard@savoirfairelinux.com>