batman-adv: init script tries to retrieve interfaces from uci

batman-adv: init script tries to retrieve interfaces from uci

The batman-adv init script will query uci (network.$iface.ifname)
to retrieve the interface name to re-use the existing network
configuration system.
The default iface configuration (batman-adv.bat0.interfaces) is
set to 'mesh' which allows to start batman-adv as soon as the
network configuration contains a 'mesh' stanza.

Signed-off-by: Filippo Sallemi <tonyputi@gmail.com>
Signed-off-by: Gioacchino Mazzurco <gmazzurco89@gmail.com>
git-svn-id: svn://svn.openwrt.org/openwrt/packages/net/batman-adv@26719 3c298f89-4303-0410-b956-a3cf2f4a3e73