Add blueprints for "ember-cli-mocha >= 0.12.0"

[Turbo87]

[email protected] introduced a new testing API and deprecated the old describeXXX() helpers. The blueprints in this repository need to be updated to reflect those changes.

Instead of just updating we should make sure that uses with all versions of ember-cli-mocha get the right blueprints. We can accomplish that by checking the installed version of ember-cli-mocha using a VersionChecker and then deciding whether to use the mocha-files or mocha-0.12-files blueprints folder.

The tracking issue for this is ember-cli/ember-cli-mocha#142

[Turbo87]

This is blocked on emberjs/ember.js#14667 and emberjs/data#4689 being resolved first