Wfs client fixes

This fixes bugs in the WFS client provider to work better with http://wfs.data.linz.govt.nz. The following issues have been fixed:

* WFS layers added from the browser no longer prompt the user for the layer coordinates system
* Ensure progress dialogue shows for WFS GML requests - especially in the case that the geometry type is not determined from the server describe feature type request and we need to inspect the feature type first feature
* If a network request error occurs while reading the streamed GML, then return a failure status from the getFeatures method
* Re-write MimeData Uri concat and split function to deal with layer names and urls that contain the ':' character. e.g "Airport/airfield points (Hydro, 1:4k - 1:22k)"