Contentful's JavaScript SDKs have TypeScript support

[realityking]

Both of Contentful's JavaScript SDKs have type files and thus support TypeScript:

• https://github.com/contentful/contentful.js/blob/master/index.d.ts
• https://github.com/contentful/contentful-management.js/tree/master/typings

[Jotschi]

Thanks for the PR.