RS Sample updated: added some configuration options

- Added arguments to configure MQTT host and port
- Added argument to configure framework UID
- Caller framework UID is printed in the greeting message
- Remote services are called in a thread, to avoid locking iPOPO.
Added tests for the dispatcher servlet
Corrected documentation strings

... according to epydoc
Support pipes in Shell environment variables test

The test was failing if an environment variable had a pipe in its value.