Checkbox/Radio button does not have any indicator to show its focus state

[thanhpd]

Bug, feature request, or proposal:

Bug

What is the expected behavior?

Checkbox/Radio button has focus ripple in focused state

What is the current behavior?

Checkbox/Radio button does not have any indicator to show its focused state

What is the use-case or motivation for changing an existing behavior?

• Usability
• Material spec: https://material.io/guidelines/components/selection-controls.html

Which versions of Angular, Material, OS, browsers are affected?

Material 2-beta1

[crisbeto]

This has been fixed in #1730 and #1731 although those PRs should be freshened up a bit.