Add error pages to Identity

Identity doesn't currently have a webserver in its stack so we're
leakign Play messages to clients. We'll review the stack but in the
meantime this provides standard Guardian error pages on production,
tweaked so they work over https.
Merge branch 'master', remote-tracking branch 'origin'
Merge branch 'master' of github.com:guardian/frontend
CSS floats for positioning
Add responsive viewer
Button tweaks
View, not Preview
Rename breakpoints
Refactor. Only pass a single config in queryStr.
Merge remote-tracking branch 'origin/facia-tool-rename' into facia-tool-rename
Merge branch 'facia-tool-rename' into facia-tool-viewer
Bullet points are not indented
Add OpenGraph image to Content model
Tweak GraphicksMagick command
Move common functionality into bast AuthAction trait
Add constraint, AuthAction needs to be mixed into a Controller
Add extraOpenIDParameters to LoginController
Add PAPE into extraOpenIDParameters for facia-tool forcing login after logout
introducing beacon url property

The beacon url is was derived from the domain of the current page, this will not work in identity as it is on a different domain. This property will fix the beacon domain, and make it protocol relative making it usable from id pages.
Use element-assets in the picture cleaner
Merge branch 'master' of github.com:guardian/frontend