Fix the 'www.' strip changing the lstrip method by the replace

If the domain name is something containing a 'w' as 'wgs-dev.amazon.com', lstrip with 'www.' removes the 'w' giving 'gs-dev.amazon.com'. The domain is then corrupted.
I propose to simply replace 'www.' by ''. 
It is also possible to check that the domain starts with 'www.' and then uses domain[4:]