[FIX] website_twitter: IE does not accept twitter date format

Datetime like Tue Jul 13 23:18:36 +0000 2010 is not accepted by IE and return "Invalid date".
Therefore, We parse the date to a format known by IE (and other browsers)
Trick took from http://stackoverflow.com/questions/3243546/problem-with-javascript-date-function-in-ie-7-returns-nan