Don't watch files controlled by JSON API server
Don't watch files controlled by JSON API server

This fixes the issue when test-data.json is modified
by JSON API server and webpack thinks the application
source has changed, triggering an automatic reload.

Signed-off-by: Vojtech Szocs <c84ddee24d9ec6bf57c82d34e0d78c578d566b77@gmail.com>

vojtechszocs/react-playground,vojtechszocs/react-playground