Add timeout to email task
Add timeout to email task

Email task needs a timeout, as there were some cases where celery caused the
task to hang.

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