Fix IntelliJ compilation oddity

The code as it was does not build in IntelliJ, although the IDE editor
does not detect there is a problem; only at compile time. The change
fixes the compilation issue without changing the behaviour.
Change junit references to TestNG

All probably the result of accepting an IDE's suggested `import` without
looking closely!
brooklyn-software-osgi, change OSGi dependency ref

Was previously org.osgi:core:4.3.0; changed to
org.osgi:org.osgi.core:4.3.0 to match usage/launcher/pom.xml reference
to OSGi
Fix interior version conflicts - qpid
Fix interior version conflicts - slf4j
Fix interior version conflicts - MongoDB
Fix interior version conflicts - maven-war-plugin
Missing dependencies on TestNG
Specify version numbers in root pom.xml only

This removes any hard-coded version numbers from pom.xml except for the
root; the root contains a set of properties that define version numbers.

In some cases this will change the minor version used; where this
happens, the version used will always move forward, not backward; and
the major version does not change.
This closes #50