Modifying the json parser so as not to escape unicode characters over u00FF

The json parser had explicit unescaping for unicode characters, which was fine only for characters which fit in UTF8. All of the json passes through erlang:list_to_binary/1, which will error out with badarg when it encounters u0100 or higher (http://www.erlang.org/doc/apps/stdlib/unicode_usage.html#id60884). 

PR consists of 54f798b containing the "re-escape u0100 and higher" functionality + test, and d91c0ee which is the output of leex on my machine (parsetools 2.0.9).