Merge pull request #2175 from minrk/staticfile add FileFindHandler for Notebook static files * The static file handler now uses a search path, instead of a single dir. This allows easier customization of available js/css, and provides a place for extra files to go for extending the notebook. * An empty custom.js / custom.css are added to the templates for trivial custom user styling/scripting. The search only happens once, and the result is cached after the first. * A few methods are pulled from tornado 2.2-dev verbatim to have tornado 2.1 compatibility. * mathjax is now installed by default in profile.