[NFR] Category view

[pgasiorowski]

Random thoughts for initial work:

• Name, Description on the top
• List of subcategories
• List of threads, each row showing:
  • thread title
  • count of posts
  • author
  • date of first and last posts
• New topic form
• Read-only mode
  This will be useful for these times when some database maintenance (like reconfiguring master in replication etc.) is needed and instead of taking whole site down we would only make the forum read only. Something alike stackoverflow dows - you can read, but you can't post. Btw, this would be nice in the core too - to stop registration etc..