Email validation for long TLD's

[tomjanssens]

The HTML5 type="email" validation doesn't yet work for longer TLD, example: .brussels.

Check if we can overwrite the default validation regex pattern using the pattern attribute to extend the length of the TLD.

See: http://www.w3.org/TR/html-markup/input.email.html#input.email.attrs.value.single

Reported by 5342-11