use typescript parser for parsing js files instead of espree

[kvantetore]

By using typescript to parse js files we can parse files with typescript or flow type annotations.

I have an implementation in kvantetore/angular-gettext-tools@3130c38, that passes all the tests.

It's all tangled up with #105, but I can create a PR if there is any interest

[nkobber]

Would appreciate if you did

[Toilal]

It would be great to bring TypeScript support, as it's more and more common to use it, even with AngularJS (1).