Make the form more useable

[danielabar]

Form guidelines: https://govuk-elements.herokuapp.com/form-elements/

Various form improvements including:

• alignment
• help text
• reset button
• input validations -> actually, maybe pull this out to its own ticket, otherwise gonna get too big here
• figure out behaviour when form field is blanked out then submitted, should not allow submit
• make button look more like button (maybe something like stripe buttons: https://stripe.com)