Set Content-Type header for console logs (#523)

Author: basil

src/main/java/io/jenkins/plugins/pipelinegraphview/consoleview/PipelineConsoleViewAction.java

@@ -130,6 +130,7 @@ public HttpResponse getConsoleText(StaplerRequest req, StaplerResponse rsp) thro
 
             Writer writer;
             if (count > 0) {
+                rsp.setContentType("text/plain;charset=UTF-8");
                 writer = (count > 4096) ? rsp.getCompressedWriter(req) : rsp.getWriter();
                 spool.flush();
                 spool.writeTo(new LineEndNormalizingWriter(writer));