Merge pull request #9 from ag-csw/master

pull
Merge pull request #10 from ag-csw/master

Refined xml canonicalization.
Merge pull request #12 from ag-csw/recursive-ralph

Recursive ralph
adding case P to the list of test cases
writing out XMLCatalog only if it contains at least one mapping
Merge pull request #17 from greenTara/recursive-ralph

fixing issue #13