Support badge `maxAge` (fix #3000 and #1612)
Support badge `maxAge` (fix #3000 and #1612)

Pass on the `maxAge` query parameter when redirecting to the badge image
from Shields.io. This should help with GitHub's unwanted badge caching.
The default is 1 day.

pombredanne/readthedocs.org,rtfd/readthedocs.org,davidfischer/readthedocs.org,safwanrahman/readthedocs.org,safwanrahman/readthedocs.org,rtfd/readthedocs.org,safwanrahman/readthedocs.org,pombredanne/readthedocs.org,pombredanne/readthedocs.org,rtfd/readthedocs.org,davidfischer/readthedocs.org,rtfd/readthedocs.org,davidfischer/readthedocs.org,safwanrahman/readthedocs.org,davidfischer/readthedocs.org