Changes to functionality
- Removed syncing of user metadata including gender, location etc.
These are no longer available to standard Facebook applications.
- Removed the remote 'revoke' functionality. No other providers have
it, and it does not appear to be standard practice in other apps.
- The 'facebook_no_email' event is no longer logged. The system can
cope fine with a missing email address.
Data is migrated to the new user_associated_accounts table.
facebook_user_infos can be dropped once we are confident the data has
been migrated successfully.
- By default, behaviour is not changed: tags are made lowercase upon creation and edit.
- If force_lowercase_tags is disabled, then mixed case tags are allowed.
- Tags must remain case-insensitively unique. This is enforced by ActiveRecord and Postgres.
- A migration is added to provide a `UNIQUE` index on `lower(name)`. Migration includes a safety to correct any current tags that do not meet the criteria.
- A `where_name` scope is added to `models/tag.rb`, to allow easy case-insensitive lookups. This is used instead of `Tag.where(name: "blah")`.
- URLs remain lowercase. Mixed case URLs are functional, but have the lowercase equivalent as the canonical.
