Travis CI integration
daemon: Encode the lifetime of bundles into the prophet acknowledgement set
daemon: Moved the relabel() call of clients into Registration::processIncomingBundle()
ibrdtn: Relabel bundles with a timestamp of 0 if the clock rating is 0.0
daemon: Always create DT-NTP and routing bundles with a timestamp of 0 + age block
daemon: Changed text of warnings if the local clock seems to be wrong
ibrdtn: Bad clock property and fuzzy expiration removed

A local clock is assumed to be wrong if the rating is 0.0. 
Fuzzy expiration is removed, now a bundle is treated as bundle with right values or is
expired relatively to the local time.
daemon: No longer add age blocks to incoming bundles
daemon: Replace bad clock settings with rating = 0.0 call
daemon: Check incoming bundles for expiration in the validator for the primary block

The validator of the primary block can check bundles without an age block
(timestamp > 0). If the timestamp is set to 0, the validator will accept the bundle
and check it again if the complete bundle is available.
daemon: Add NACK support to DatagramConvergenceLayer

The transmission of an rejected bundle will be stopped and the
bundle is marked as refused. So no further transmission of that
bundle will be started. Invalid incoming bundles are skipped but
acknowledged, until there is a way to transmit an unambiguous
NACK.