Adding KerberosHelper
Refactoring IEntityManagerHelper.get* methods to take a optional username.
Changing rest of the calls to take username as parameter.
Adding user option to Bundle.submitClusters().
Adding simple multi-user test.
Fixing minor issues.
Minor fix for testing.
Avoid unnecessary kinit calls.
Cleaning up example.
No-op when kerberos is off.
Adding log messages.
Minor change to dummy command.
Addressing review comments.
Adding log if kerberos is disabled.
Use static variable for user2.
Adding assertion.
Moving constants to MerlinConstants class.
Renaming test.
Better name for static variables.
Simplifying kerberos enabled detection.