Setup static aliases to point to current dirs.
Setup static aliases to point to current dirs.

Previously requests to e.g.
static.preview.alphagov.co.uk/calendars/calendars.css would be aliased
to calendars' DEPLOY_ROOT/shared/public/calendars.  This relied on a
post-deploy task that symlinked the current/public directory into
shared/public.

Given that the asset pipeline (when configured correctly) symlinks
public/calendars to shared/assets we can safely just point at the
current/public/calendars directory.  This will contain all the assets
(including ones from previous deploys).  This will remove the need to
iexplicitly symlink stuff in the deploy scripts and will make
configuring new apps simpler.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet