Easing help request validations

Prior to this change, the /404 page for Curate was rendering and
throwing a silent error (with a redirect to the help request form
without a meaningful error message).

Also ensuring that when a user submits an invalid form, that the
submitted values are preserved (instead of obliterated).

@JIRA DLTP-269 #under_review
Merge pull request #71 from jeremyf/easing-help-request-validation

Easing help request validations