Add TypeScript definitions for moment-msdate methods

[andymerskin]

Using moment-msdate in place of moment or moment-timezone in a TypeScript project requires type definitions for its methods. Moment + Timezone are already typed.

I'm still pretty new to TypeScript, but I may create a PR we can review and hopefully get this in.

All it may involve is (add anything I'm missing)

• [ ] Create TS def file moment-msdate.d.ts
• [ ] Link to package.json on typings key