root package.json needs to be cleaned up

[stevengum]

Versions

master branch

Describe the bug

The package.json at the root of the project can be cleaned up:

1. Old dependencies
   • ms-rest-js and ms-rest-azure (these packages are now namespaced under @azure)
2. Version mismatches between dependencies and devDependencies
   • dependencies: "typescript": "^3.1.1"
   • devDependencies: "typescript": "^2.7.2"
3. It's unclear why we have devDependencies in the root package.json as these dependencies are most likely going to be installed anyways when a developer forks and clones the project. Instead of devDependencies and dependencies, there should just be dependencies.

Additional Context

Originally found in #925

[bug]