Add functions to print ExecutionPolicies in a standard way

Improves 3e6fe06d97aa
Define to_string() and operator<<() in namespace std for handling rosa::deluxe::DeluxeExecutionPolicy. Adjust log code in the example deluxe-interface and add tracing info to rosa::deluxe::DeluxeSensor::setExecutionPolicy() and rosa::deluxe::DeluxeAgent::setExecutionPolicy().