Generate proper bridge port configuration

bnc#879617

* Removed workaround for sysconfig (0.0.0.0/32).
* Huge cleanup.
* Updates for testsuite
better to use reduce here and also concat which is more efficient:
```
confs = (NetworkInterfaces.CardRegex["netcard"] || "").split("|").reduce([]) do |res, devtype|
  res.concat((configurations[devtype] || {}).keys)
end
```