Ignore build artifacts

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1538360 13f79535-47bb-0310-9956-ffa450edef68
FELIX-3861 Assign the plugin to the "OSGi" category

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1538361 13f79535-47bb-0310-9956-ffa450edef68