Closing/opening topics

As a moderator I'd like to be able to close topics to restrict others from continuing topic in order to escape flooding in/polluting of useful topics
Acceptance Criteria:

• If I have CLOSE_TOPICS permission for branch, I can close topics in particular branch, i.e. button is visible
• If I have CLOSE_TOPICS permission for branch, I can open topics closed in that branch and people will be able to post there again
• Closed topics should have different icon in the topics list intuitive enough to understand that the topic is closed.
• Closed topics that have new posts in them should have the same icon, but with different hue so that people understand both that the topic is closed and that there are unread posts there.
• Users still will be able to vote even if topic with poll is closed, but they won't be able to leave new posts in there.
• It doesn't affect any other functionality but posting replies, the topic should still behave the same as others (can be moved, deleted, it's possible to see it in recent activity and RSS, etc).