Fix date_formatter test
Fix date_formatter test

When deciding the UTC offset to contruct the regex that checks
proper UTC formatting, the tested date should be used instead
of the current date.

hobbyquaker/homematic-xmlrpc,baalexander/node-xmlrpc,Growmies/node-xmlrpc,patricklodder/node-xmlrpc,bolster/node-xmlrpc,xmlrpc-js/xmlrpc-marshalling