Handled xlink namespace and added ShortJobDescriptionTest

src/main/java/net/ivoa/xml/uws/v1/package-info.java

src/main/java/net/ivoa/xml/vospace/v2/package-info.java

src/test/java/net/ivoa/xml/uws/v1/JobSummaryTest.java

...est/java/net/ivoa/xml/uws/v1/ShortJobDescriptionTest.java