Admin users and dashboard

[benjaminpjones]

Elevated privileges for some users could be useful in many ways, but one of them would be the ability to take a common bulk action on games from a UI. For example:

• Change the name of a variant in the database
• Remove invalid moves from games (if, a variant's rules become more strict)
• Unseat inactive/guest users
• Delete games with no moves

Besides bulk db manipulations, admin users might be able to do things like:

• View analytics
• Moderation tools like delete game or user