fix bug 834300 - attachments from ATTACHMENT_HOST

Only serve raw attachments when requested on the ATTACHMENT_HOST as configured
in constance.
(some) pep8 cleanup
fix bug 779499 - Implement legacy redirects
Merge pull request #849 from darkwing/legacy-redirects-779499

fix bug 779499 - Implement legacy redirects
fix bug 810362 - Add dash link
Merge pull request #850 from darkwing/dash-console-810362

fix bug 810362 - Add dash link
move from constance to settings
fix bug 834384: Include demo search terms in pagination links when needed
Merge pull request #851 from lmorchard/834384-search-terms-in-pagination

fix bug 834384: Include demo search terms in pagination links when needed
Merge pull request #847 from groovecoder/attachment-host-834300

fix bug 834300 - attachments from ATTACHMENT_HOST
Adding promo-block in homepage and images
Chnge URLs in home promo blocks (bug 838224)
Adding focus/active link states, fixing test, cleaning up python template
Merge pull request #1 from darkwing/bug-838224

Adding focus/active link states, fixing test, cleaning up python template
Updated Firefox for Devs link
Merge pull request #2 from darkwing/bug-838224-dos

Updated Firefox for Devs link
Fix bug 840256: Use full Sitemap path in robots.
fix bug 840052 - let DOMAIN iframe attachments
Merge pull request #854 from openjck/robots-sitemap-path

Fix bug 840256: Use full Sitemap path in robots.
Merge pull request #853 from tx2z/bug-838224

Bug 838224 - "Interim" homepage banners (to support MWC)