Sanitization "out of range" strings

Some strings siuch as one generated by `$invalidString = urldecode('%00%01%02');` will cause the generated XML properties document to be invalid. This PR fixes that.

I thought about adding this as a `phpcr-api-test` but wasn't quite sure how that would fit in. `10_Writing/AddMethodTests` but then this would be an "Add" then "Read" test. So, have just added a test for doctrine-dbal.