ice: new ice message format

WARNING: this patch breaks the compatibility of ICE message format.

This patch introduces a new ICE message format to serialize
ICE transport information.
This format permits futur evolutions of this functionality by:
 - adding a version tag to indicate the format used
 - use msgpack to have a compact and easy way to handle data

Change-Id: I1df6197e487ec119cf55a34fc531d2514f6fcf16
Reviewed-by: Stepan Salenikovich <stepan.salenikovich@savoirfairelinux.com>