Update intern.json so it can be used with both grunt and intern commands

[bryanforbes]

Type: enhancement

The following has been addressed in the PR:

• [ ] There is a related issue
• [x] All code matches the style guide
• [ ] Unit or Functional tests are included in the PR

Description:

Updates intern.json so that using both ./node_modules/.bin/intern and grunt intern will properly load the @dojo/shim patches for tslib.