[BZ-1127999]  JBOSS JSP class loading problem due to case insensitivity

realRoot must be canonical. When getFile is invoked and the 
realRoot provided is not the exact match the vfs creates a 
non-canonical form of the file. This could lead when the flag
-Djboss.vfs.forceCaseSensitive=true is set to fail on windows.
(this happens when the realRoot comes from an env vars, i.e jboss.server.temp.dir)