NXCM-5424: Added p-u as direct dependency of the plugin

As SecDispatcher mojo commons uses to decrypt passwords
need it, and older versions of p-u lacks XmlStreamReader class
NXCM-5424: Moved dep near to it's user
Merge pull request #47 from sonatype/nexus-5424-add-p-u

NXCM-5424: Added p-u as direct dependency of the plugin