Add tracking of whether banner has been viewed
Add tracking of whether banner has been viewed

It was reappearing on every new page load even after being dismissed.

Supports opengovernment/product#44

mapineda/askthem,opengovernment/askthem,mapineda/askthem,opengovernment/askthem,mapineda/askthem,opengovernment/askthem,opengovernment/askthem,mapineda/askthem