Report moderation

    - redaction marked with [...]
    - of report and comments
    - stores original data
    - uses a single form, on the report/_main view
    - requires additional permissions (user_body_permissions)
    - Hide report functionality
    - Moderation notification/contact form
    - Moderation writes to admin_log
Tests for moderation
Move bromley from report hiding to moderation

The feature to hide reports is still enabled, as it is used by other
`users_can_hide` bodies.  As we want to roll out moderation to Bromley,
in this commit we hide the functionality *only* for Bromley.  Of course
if we migrate those other users to this moderation method, then we will
need to make equivalent change to general template, and remove the
functionality from Report.pm.
refactor repeat code into get_email_template
Moderation - update-schema fixed and improved

    bin/update-schema --commit should now work

A downgrade is also provided.  Run bin/update-schema --help for details