Merge pull request #47 from zorun/babeld_configfile

Updates to babeld

This patchset:
- fixes #33 by generating a configuration file for babeld
- introduces a slightly different syntax for specfiying interfaces (backward-compatible)
- allows to use any option, as long as it's supported by babeld (i.e. valid options are not hardcoded in the init script anymore, all options are simply passed to babeld)

It is mostly backward-compatible, with a few caveats.

Thanks to Baptiste Jonglez.