Discovered that trying to access SecurityContextHolder information was broken inside CherryPy app

While working on case study for the book, discovered that I was unable to access the SecurityContextHolder information due to it being cleaned out before reaching the CherryPy view code. Had to write custom page handler inside CP3FilterChainProxy in order to properly handle the function call at the right entry point.

Turned out to not be a huge impact to the code, even though it took me hours to figure out the solution.