The implementation of URL parsing for retina gravatars was incredibly clumsy if

the user was using any of the extra parameters which are available in settings.

For example, if the user had set GRAVATAR_DEFAULT to something fun, retina

users wouldn't see it because it wouldn't preserve the d= param.
This change makes the parameter parsing much more capable, fixing the size

parameter without touching any of the others.

Set GRAVATAR_DEFAULT to 'wavatar' in my settings_local.py file and saw actual

wavatars instead of the ugly Gs.