Read/Write support for the DataAvailability tag in StationXML and update to FDSN WS 1.1

This PR adds read and write support for the `<DataAvailability>` tag in StationXML files.

It furthermore updates `obspy.fdsn` to support the 1.1 standard. It will still work with older implementations but it will complain about missing parameters which is fine in my book. The only real change to 1.0 is the addition of the `matchtimeseries` parameter.

I furthermore updated all test which starts to get annoying...
Do you mean the ones around the string including its formatting? Yea..they are strictly speaking unnecessary but it is one statement with the line below and I tend to but parenthesis when the operator precedence is not really intuitive to ease readability. I would actually like to indent the line below that one more level as that would be clearer IMHO but then PEP8 complains...