[MERGE] [FIX] website_forum: batch of fixes :

- fixed reopen link that was broken (python code appearing)
- fixed close link that was leading to a 500 error due to post -> question
- fixed link to question author, was redirecting to the current user
- fixed displayed number of questions in the forum, now displaying actual question
number, not number of displayed questions in the page
- improved guidelines: added link back to the forum
- fixed tags display: now by posts_count desc, unused tags are not shown
- users are now displayed by desc karma
- converting a comment as an answer does not allow to create a new answer if another
one by uid is already present, it just moves the comment
- display tag name in 'filter' bar when filtering on a tag
- display active tag in a blue color
- order answers: correct first, then most upvoted

bzr revid: tde@openerp.com-20140506150145-c1uvlaqtyvkjcwea