Fix submit buttons staying disabled after cancel from set-password and re-submit with same email address.

* Remove the "submit_disabled" class on the body when address info retreival is complete.
* fixes #3431
Merge pull request #3433 from mozilla/issue_3431_disabled_submit

Fix submit buttons staying disabled after cancel from set-password and re-submit with same email address.

@seanmonstar gave the r+, merging.