Revert "Fix #658 content type for full size cover arts"

This reverts commit 18b16eb859.

airsonic-main/src/main/java/org/airsonic/player/controller/CoverArtController.java

@@ -217,7 +217,7 @@ public class CoverArtController implements LastModified {
 
     private void sendUnscaled(CoverArtRequest coverArtRequest, HttpServletResponse response) throws IOException {
         File file = coverArtRequest.getCoverArt();
-        if (jaudiotaggerParser.isApplicable(file)) {
+        if (!jaudiotaggerParser.isApplicable(file)) {
             response.setContentType(StringUtil.getMimeType(FilenameUtils.getExtension(file.getName())));
         }
         InputStream in = null;