Updated the documentation to contribute to the project.

- Updated the section about the global environement installation
- Fixed, completed and detailed the full procedure to setup the Eclipse project and launch it

For now the use of the backend inside the Eclipse plugin is still failing for partly known reasons.
Updated procedures to launch the Eclipse application and the backend.

- set up a development state where the Eclipse plugin can edit HTML files
- fixed last LiveScript dependencies by loading the LiveScript engine at start
- now using `npm start` is the prefered way to launch the backend

Some of these items introduced or brought out some issues that are going to be fixed.