Revert "ref #7276 revert "make User.email a unique field""
This reverts commit 80cbc74164e5b37dbaa8e64d90126e745a9a05e3.
Revert "ref #7276 revert "make User.email a unique field""
This reverts commit 80cbc74164e5b37dbaa8e64d90126e745a9a05e3.