Conform to Rack conventions: Rename /static dir to /public. Add /tmp dir...

Hi, to make Kibana easier to deploy under the popular Passenger application server only a few simple changes were needed, since Kibana already uses the Rack interface.

Passenger assumes that Rack application directories have a certain simple layout. See: http://www.modrails.com/documentation/Users%20guide%20Nginx.html#deploying_a_rack_app

I basically renamed /static to /public, created a /tmp dir, and made one change to kibana.rb. I have this setup running nicely on my nginx+passenger server.

Passenger is quite a popular way to deploy Ruby apps, so this change could benefit many people who already have an Apache or Nginx server running and would like to avoid running yet another Ruby webserver.

Would you please consider merging this into your mainline repo?

Regards, Martijn Heemels