Added .gitignore to support users with git-svn and working on github mirrors

git-svn-id: https://svn.apache.org/repos/asf/struts/struts2/trunk@1520781 13f79535-47bb-0310-9956-ffa450edef68

.gitignore

@@ -0,0 +1,52 @@
+core/target
+xwork-core/target
+archetypes/struts2-archetype-angularjs/target
+archetypes/struts2-archetype-blank/target
+archetypes/struts2-archetype-convention/target
+archetypes/struts2-archetype-dbportlet/target
+archetypes/struts2-archetype-plugin/target
+archetypes/struts2-archetype-portlet/target
+archetypes/struts2-archetype-starter/target
+archetypes/target
+plugins/convention/target
+plugins/embeddedjsp/target
+plugins/dojo/target
+plugins/osgi/target
+plugins/cdi/target
+plugins/codebehind/target
+plugins/spring/target
+plugins/jfreechart/target
+apps/rest-showcase/target
+apps/mailreader/target
+apps/portlet/target
+apps/blank/target
+apps/jboss-blank/target
+apps/mailreader/target
+apps/portlet/target
+apps/showcase/target
+apps/target
+bundles/admin/target
+plugins/config-browser/target
+plugins/jasperreports/target
+plugins/jsf/target
+plugins/json/target
+plugins/portlet-tiles/target
+plugins/portlet/target
+plugins/sitegraph/target
+plugins/sitemesh/target
+plugins/struts1/target
+plugins/tiles3/target
+plugins/javatemplates/target
+bundles/demo/target
+plugins/rest/target
+plugins/plexus/target
+plugins/testng/target
+plugins/dwr/target
+plugins/gxp/target
+plugins/oval/target
+plugins/junit/target
+plugins/tiles/target
+bundles/target
+plugins/target
+target
+plugins/testng/test-output