Fixed action=query list=blocks for IPv6 addresses

Fixed action=query list=blocks for IPv6 addresses

Queries like the following return wrong rangestart and rangeend
data cause the IP addresses are formated with only IPv4 in mind.
As IP::formatHex is able to format both I've switched over to
that.

Example:
http://en.wikipedia.org/w/api.php?format=xml&action=query&list=blocks&bkprop=range&bkip=2002%3AB752%3AD225%3A0%3A0%3A0%3A0%3A1

Change-Id: I6138240bb03bbf5af61851d3e96354a050e56fed