Require address when submiting payment form

By default, we use HTML5's validation to require the fields. If the user
already has a bank account registered, we don't require "bank form" to
be filled. After form submition, the 'novalidate' attribute is added to
the form, allowing us to submit the form without bank account fields
(cleaned after sent to Balanced).
Merge pull request #46 from neighborly/im-require-address

Require address when submiting payment form