Make the toggle-switch usable with keyboard or assistive technology.

[phw]

Adding the functionality required for the ARIA switch role allows using the switch with keyboard or assistive technology.

• Add role="switch"
• Allow toggling the switch with space key
• Set the aria-checked attribute dynamically
• Made the switch focusable by adding the tabindex attribute (can be overwritten)

See: https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/ARIA_Techniques/Using_the_checkbox_role https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/ARIA_Techniques/Using_the_switch_role

[phw]

Sorry, will fix the tests.

[phw]

I have fixed the unit tests and called grunt build. The unit test still failing is just the tests are failing on master, too. As this is unrelated to this feature pull requests I added another one just for the existing unit tests: https://github.com/JumpLink/angular-toggle-switch/pull/15

[JumpLink]

Thank you again :)