added layout code

Moving the newsletter box, part of #1165
added new layout for pages

Thirds variant of major/minor layout
Styled newsletter box

Now moved position, tidied up existing markup used previously
Closes #1165
Accessibility fix for email signup

Label is now present but visually hidden - still accessible to screen readers etc
Added feedback text to org detail page

Closes #1170
Merge remote-tracking branch 'origin/issues/1165-update-monitor-page'
replaced logo file with updated tagline
Merge remote-tracking branch 'origin/issues/1161-change-tagline'
Merge branch 'issues/1170-constituency-office-feedback'