Fix for subscription start date / end date issues...

For some reason, if I don't add the save line here and the end date is a year away, the subscription start and end date default to today, as if it was never set...

I tried digging into this and couldn't for the life of me figure out why, and why _specifically_ for an end date that was a year away, as the subscription IS saved in `new_domain_subscription` and `date_start` and `date_end` are set. If anyone has ideas, I'd love to hear. Otherwise, this is the fix.

This fixes http://manage.dimagi.com/default.asp?120385