[Doc][Config] Changes documentation, configuration and some utility 

@catchamonkey 

This PR updates run_tests.sh adding phpunit and handling the cache in the test environment.
Updates the documentation, adding information for the new features and changing the README.md in order to provide more clear information to potential external users.
With this PR now emails must be set in the configuration

```yaml
# /app/config/config_test.yml
infinity_test:
    recipients:
            - email1@example.com
            - email2@example.com
```

and can be overwritten in parameters.yml so to restrict the submission of emails to you only when working in your dev container