SPRIN-1 Showcase the use of roles.

Added role-based authorization example (maybe switching to el-based access rules was a bit forward, but I'm not even sure how it should be done without it).

Jamy, is it possible to add roles in the casinthecloud provider? I tried setting up my own but couldn't find it. (perhaps it's possible when coupled to LDAP, but I can't spare the time to set that up right now)