Fix HTML5 validation errors
Clean up form validation errs for phone number
Re-add display of the number of validation errs found

* contact_form.jade: Add errs anchor & action link for jumping
to the number of validation errors message upon form submission.

* contact_form.jade: Fix layout issue by re-adding the input_container
class within a div; the widths for the form elements must inherit from
the parent (input_container), otherwise we are ~4% over on the right
margin.