Admin: Read/write permissions for robots

[mayacakmak]

Currently any user can edit content of a robot. This means someone could spend a lot of time making a robot work and someone else can come and mess it all up unintentionally. To avoid this, I propose:

• Add a list of admins to each robot on the database; robot->admins, this could be email address and we could require Google sign in. It could also be anonymous uid (though those can change even using the same browser on the same machine). If we do this, maybe more the 'sign in with google' button somewhere else on the front-end tools page.
• Change the setup tool to only work for users who are admins on a robot.
• Only admins of a robot should be able to add/remove programs in the programming tool (though I think currently there is no way of removing programs)

Note that non-admins should still be able to view a robot ("read") and control it through WoZ or preexisting programs (i.e. "write" onto robot state/actions, but not content like faces, screens, programs, etc).

Also:

• Update the Admin tool in the front-end so the master admins (which can only be added through the database UI) who have access to the Admin tool can add/remove robot admins.