Switch from exec to spawn to kill children and sub-children
in the same time from the main test process.
Also add some error handling, and make the program exit with error
code (1) if anything goes wrong during execution.
Change test structure
Generate new testApp from node script and launch app
Add new feature: Be able to user strapi start and specify an app path (WIP) configs are loaded
Generate test API with relations - articles, tag and category