We should use a consistent default value for the name of a component's directive controller when it is attached to the scope. See #10007 (comment)

Currently we are defaulting to the canonical name of the component. This is not ideal as

a) component names can become long and unwieldy for use in a template
b) it is more complicated to automatically update the template to be used in Angular 2, where the context is the controller.

The criteria for the name are:

1. it must be the same for all components
2. it must start with $
3. it must be short (2-4 chars)

In addition the name should represent what is actually being published to the scope.

Some of previous suggestions include:

• vm - this is the commonly used name in many applications but the controller is not necessarily a "view model"
• $comp - this is the current suggestion from the team but can be confused with compare and is not that short
• $ctrl - this can be confused with input ConTRoL elements
• $this - the controller is not really this in the template, since the context is still actually the scope