Make division policy link go back as you can get here from elsewhere

e.g. if you're on a member division comparison page, you can click
"Edit related policies" and if you click the header you're sent back
just to the division page, when I'd expect to be sent back to the
page you were just looking at.
Make member comparision page more useful. Fixes #646

By displaying the comparison statement in the header
Merge pull request #689 from openaustralia/member-division-comparison-page-header

Member division comparison page header