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Merge pull request #754 from bradh/patch-1

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[GEOS-6647] Failure to generate WMS capabilities document when cascading a WMS server that does not advertise GetFeatureInfo
GEOS-6668: Fix WMS 1.1.1 CITE failure.

This modifies the DTD to match the new CITE requirements (per CITE-866).

An alternative implementation would be to get the http://schemas.opengis.net/wms/1.1.1/capabilities_1_1_1.dtd
version and copy that in, instead of modifying the existing file. Slightly different implementation, same effect.