Merge pull request #160 from odoo-dev/master-forum-subtypes-tde

MERGE [IMP] website_forum: make forum.forum inherit from mail.thread. This way we add the possibility to users to follow a forum and be automatically followers of new questions, using some new subtypes on the forum.forum model that do the auto subscription.

Misc :

also added a profile link on the forum, when logged.
also added a subscribe button on the forum.