batman-adv: Move IRC channel to hackint.org

Due to recent developments around the Freenode.org IRC network, the
opinions about the usage of this service shifted dramatically. The majority
of the still active users of the #batman channel prefers a move to the
hackint.org network.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>