[INTERNAL] made member fields of User class private

Also replaced equals and hashcode methods with newly generated 
methods. (Who put that log statement into the equals method ? oO)

Change-Id: I72f6e0f492c3272e9450e12f2e8da7d6d98099aa
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/911
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>