Fixes #7 GML namespace issue with libxml2 2.8.0

The GML namespace is stripped from elements before they are passed to
st_geomfromgml
Added unit tests for DiskCachingRequest parser

As per review
Whitespace tabs to spaces
derpa derpa remove commented code
Whitespace indent fix
Merge pull request #8 from aodn/gml-namespace-removal

Fixes #7 GML namespace issue with libxml2 2.8.0