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.
Change db name.
Make User __init__ less weird.
Be more defensive for avatar url.
Nuke the entire session object when logging out.
Pep8.
Explicitly test against an empty value for username and avatar_url.
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
Construct the thanks URI dynamically based on env.
Add a "home" link to the thanks page.

The top left header image isn't super obvious.
Very small edits/fixes
Very small edits/fixes
Added 'required' attribute to required form fields
Change of opacity on submit buttons and make disabled on empty field
Merge pull request #139 from tagawa/docs

Very small edits/fixes to CONTRIBUTING.md
Merge branch 'dev.webcompat.com'

* dev.webcompat.com:
  Very small edits/fixes
  Very small edits/fixes
Merge branch 'form' of github.com:tagawa/webcompat.com into tagawa-form

* 'form' of github.com:tagawa/webcompat.com:
  Change of opacity on submit buttons and make disabled on empty field
  Added 'required' attribute to required form fields

Conflicts:
	webcompat/templates/form.html
Merge branch 'dev.webcompat.com'

* dev.webcompat.com:
  Change of opacity on submit buttons and make disabled on empty field
  Added 'required' attribute to required form fields