Adds tests for the Webrunner, and updates its code to make it easier to test. These tests are still incomplete, but they have the merit of existing. I don't really like mocking function calls, but globally it's a better way than spawning a supervisord server and recreating the whole slaprunner's system tree.
Also adds tools (= scripts) which will be usefull for the monitoring in slapos :
- generation of RSS feed from status items, and management of them.
- script for creating promises based on RSS feeds