DDSXML — Add OMG URL to schemaLocation attributes

SchemaLocation attributes in the machine readable XSD and XML files reference documents in the working directory. This works well then he documents are local and the documents that are being included are in the working directory. However, because these files are going to be uploaded to the OMG servers, we must add the URLs to ensure that inclusions and imports will always work.

This FTF must generate its report in May of 2018; therefore, the URL where the XML and XSD files will end up being published will be the following: "http://www.omg.org/spec/DDS-XML/20180501/"

Add updated URL to schemaLocation attributes

The proposal is to prepend the files included and imported by XSD and XML files with the following URL: "http://www.omg.org/spec/DDS-XML/20180501/"