JBTIS-312 - add source bundles to SwitchYard

Add feature/ plugin source bundling support through the tycho-source-feature-plugin and tycho-source-plugin. Packaging is through the repository-utils tycho mojo requiring a change from an eclipse-update-site to an eclipse-repository.  Minimal changes made - kept kepler (updated to most recent kepler TP).  No associatedSites.