QPID-5048: add pluginManagement section to the qpid parent, to override apache parent versions as desired and set any additional config.

Sets the compiler source+target values in parent and removes unecessary duplicate compiler plugin config from child modules.


git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1527797 13f79535-47bb-0310-9956-ffa450edef68