test/cli needs to test --watch

[novemberborn]

The test for lib/watcher.js are fully stubbed so changes to the API may break the watcher without failing any tests. Need to add an integration test to test/cli.js.

The test should probably trigger a file change. We can look to nodemon for inspiration.

Since chokidar is an optional dependency the test may fail on platforms where it cannot be installed. This should cause the test to be skipped, not fail.

[novemberborn]

I'll take care of this.