Tslint: Add rule for enforcing semicolon or commas for interfaces

[fandy]

Is there a reason we can't enforce a consistent style of ending interface props? Since there isn't a benefit of using semicolons _and_ commas, I think it's useful to add a linting rule to enforce one.

I'm happy to submit a PR for this if it's wanted. Thoughts?

[ggarek]

@fandy, i think there is already a rule for this use case semicolon