Fixes issue with text obscuring validation checkmark. Ref #119

Wrap required fields in a span and append a pseudo element with icon. Icons also have been adjusted to include a white transparent gradient which will overlay the text when it is too long for the field.
Merge branch 'dstreet-long-uri-issue-119' into dev.webcompat.com

* dstreet-long-uri-issue-119:
  Fixes issue with text obscuring validation checkmark. Ref #119