Minor bug fixes

Hi!
Here is a preliminary fix for the issue geopython/OWSLib#182 in ows.py. In the future it probably should be investigated why the comment tag gets as far as `OperationsMetadata`. It should be discarded much earlier.

I also noticed a bug in the URL forming in feature/wfs200.py. The final url was missing the ? character between the base URL and the encoded request data. By passing the data dictionary as a parameter to `urlopen` the URL is formed correctly.