[ADD] website_forum: Adding Social Network Sharing functionality to shar...

...e Questions and Answers

Containing the biggest sql statement ever.

- Task: https://www.odoo.com/web?debug=#id=8601&view_type=form&model=project.task
- Pad: https://pad.odoo.com/p/r.ca4Qi9dcQZSnPQm9
There is already a /logo.png (defined in web module).
I would suggest to use this one instead of creating a new controller. (and it has a better implementation)