[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
A single query for counting the questions which are shared on any social network, two or more than two social network and calculating the probability. Possible all the computations is done at the database side.