Moved server time paid by / gifted to user calcualtion from
r2.lib.pages.ServerSecondsBar.__init__ to two separate function in
r2.models.gold.
Made use of these two functions in r2.lib.jasontemplates to supply these
values to the /user/username/about.json api.
Removed unused Link import in r2.models.bidding.
Moved Frontpage import into r2.models.PromotionWeights.filter_sr_name,
since that's the only place it's used