extended MDMRequestFilter to return content-type

Signed-off-by: Matthias Koller <m.koller@peak-solution.de>
diff --git a/org.eclipse.mdm.application/src/main/java/org/eclipse/mdm/application/MDMRequestFilter.java b/org.eclipse.mdm.application/src/main/java/org/eclipse/mdm/application/MDMRequestFilter.java
index 22ef21a..badf0fe 100644
--- a/org.eclipse.mdm.application/src/main/java/org/eclipse/mdm/application/MDMRequestFilter.java
+++ b/org.eclipse.mdm.application/src/main/java/org/eclipse/mdm/application/MDMRequestFilter.java
@@ -73,6 +73,7 @@
 			if (!matchesPassthrough(requestedPath)) {
 				InputStream in = request.getServletContext().getResourceAsStream(requestedPath);
 				if (in == null) {
+					response.setContentType("text/html");
 					in = request.getServletContext().getResourceAsStream("/index.html");
 					ByteStreams.copy(in, response.getOutputStream());
 					return;