Fix build errors in JDK1.7

I had issues building the plugin on my OSX using JDK1.7. 
1) Couldn't resolve the jenkins plugin org.jenkins-ci:annotation-indexer:jar:1.4 - resolved by adding jenkins repos
2) this error: https://bugs.eclipse.org/bugs/show_bug.cgi?id=389581 - resolved by using maven-hpi-plugin v3.0.1