Support Eclipse feature for generating a p2 repository

I've added an Eclipse feature that can be used with the mongo.jar bundle to create a p2 repository. My modifications to the build will set everything up to generate the p2 repository, but does not call the p2 publisher to actually generate the repository. I'm not sure the best way to integrate calling the p2 publisher. The call is of the form:

java -jar /plugins/org.eclipse.equinox.launcher_*.jar
-application org.eclipse.equinox.p2.publisher.FeaturesAndBundlesPublisher
-metadataRepository file://repository
-artifactRepository file://repository
-source //build/p2
-publishArtifacts

My apologies for the bad pull request - I'm still learning Git.  Hopefully this pull request will be better.