Reorganize the home page

Implementation status
Available
Targetted user
Description

Technical taks: The home page shall be made of the following sections, editable by the administrator:
- Annoucement section (not logged in) : place holder for information to the users about the purpose of the test bed and the scheduled events
- Session process section (log in): place holder for the phase-related information displayed to the user
- Documentation section (always shown): documentation the administrator has chosen to promote on the home page
It is the same page for all language (no translation)

Acceptance criteria

When the user is not logged in, he can see two distinct sections. 

The sections have different background colors for the user to distinguish both sections.

HTML  content provided by the tool administrator is displayed in each content and in the right place (announcement at top and documentation below).

When the (non-logged in) user clicks on the "home" button he is redirected back to this page.