Allow other emma-maven-plugins as precondition for Jenkins Emma Plugin

Currently the Jenkins Emma Plugin only runs if the emma-maven-plugin from org.codehaus.mojo did run before. We use the plugin from org.sonatype.maven.plugin and don't get any coverage reports in Jenkins.

Please be more liberal regarding the preconditions for running Jenkins Emma Plugin. For me the changes you can find in the attached patch-file helped to get coverage-reports, maybe checking of the groupId could be skipped completely?