Convert project to typescript

[iamareebjamal]

Steps:

Current Focus:

• New classes should target typescript
• Conversion of utils, helpers and lastly models in typescript

Long Term focus (PRs not required now):

• Convert existing components and routes when working on them heavily
• Remove remaining part of JS

https://ember-cli-typescript.com/versions/master/docs/ts-guide/using-ts-effectively
https://v4.chriskrycho.com/typing-your-ember.html

[mariobehling]

Typescript support has been added and we will expand on this.