Move stream manager package inside org.apache.jena.system.

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1612596 13f79535-47bb-0310-9956-ffa450edef68
Reflect the move of package for StreamManager to org.apache.jena.riot.system.stream

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1612599 13f79535-47bb-0310-9956-ffa450edef68