Removed quotes from the Content-Type header to support mime-type detection on android
diff --git a/system/helpers/download_helper.php b/system/helpers/download_helper.php
index 47d55db..f3f0ff2 100644
--- a/system/helpers/download_helper.php
+++ b/system/helpers/download_helper.php
@@ -91,7 +91,7 @@
 		}
 
 		// Generate the server headers
-		header('Content-Type: "'.$mime.'"');
+		header('Content-Type: '.$mime);
 		header('Content-Disposition: attachment; filename="'.$filename.'"');
 		header('Expires: 0');
 		header('Content-Transfer-Encoding: binary');