added mimetype for json files

Author: MaStr

piratebox_origin/piratebox/piratebox/conf/lighttpd/mime.types

@@ -80,6 +80,7 @@ mimetype.assign             = (
   ".oti"          =>      "application/vnd.oasis.opendocument.image-template",
   ".oth"          =>      "application/vnd.oasis.opendocument.text-web",
 
+  ".json"	 =>     "application/json",
   ".epub"	 => 	"application/epub+zip",
   ".fb2"         =>      "text/xml",