WIP work on improving feedback granularity and anti-spam measures.

 - added a type field
 - added a timestamp and honeypot check

This involved some refactoring of the signup form to generalise the
honeypot and timestamp checking constraints.

The controls to choose feedback type are not yet implemented.
Tweak i18n and form markup
Fix bad px suffix on img tag
Add alt attribute to EU logo
Merge branch 'master_guides_merge' into better_feedback
Cleanup up form binding code. Additional feedback fields still not exposed