[product: zaphod][project: zaphod-v0.3]: Don't hardcode host adapter in test.

SYNOPSIS
[modified]m42/test/test_zaphod.py: Get bridged adapter name from config file.
[modified]m42/test/yaml.conf: Specifiy bridged adapter name.

DETAILS
The test for a bridged VM requires knowledge of which host adapter to use.
This cannot easily be inferred automatically. But instead of hardcoding
this, it is better to read the info from a configuration file.