PEP8 changes.
Add implementation for test dataset Jabbeke.

And also pep8 changes.
1) Added conversion from dBz to mm/hour.
2) USe the dataset with the lowest elevation angle.
Support Jabbeke radar station.
Merge branch 'master' into jabbeke

Conflicts:
	CHANGES.rst
	openradar/scans.py
Merge pull request #2 from nens/jabbeke

Add KMI Jabbeke data