Add TypeScript bindings

[bajtos]

Add type definitions for all classes and methods exported by strong-globalize, to make it easy to use strong-globalize in TypeScript projects.

import * as g from 'strong-globalize';

const name = 'TypeScript';
// g.f has correct type definition of arguments
// g.f return type is annotated as string
const str = g.f('hello world from %s', name);
console.log(str);

Related: #113

[bajtos]

Fixed by #132