fix bug Open-Assistant #67 : submit form on enter

[seyfeddinenecib]

Adding submit of the signup form when clicking "Enter"

[yk]

hey, thanks so much for contributing :)

is there an argument for / against just making this into a form and then handling the submit? it seems like that could be a bit more streamlined than explicitly checking enter.

[yk]

for reference, you can probably just spy on #68 where I introduce another login form that uses a proper form

[seyfeddinenecib]

I implemented the changes.