Fix for issue http://evgeny-goldin.org/youtrack/issue/pl-694

When creating new maven artifact in maven-plugins/maven-common/src/main/groovy/com/github/goldin/plugins/common/ConversionUtils.groovy toMavenArtifact(), DefaultArtifactHandler is created with correct 'type' parameter to enable maven-war-plugin recognize correct artifact file extension.