IMPALA-922: Return helpful errors with Yarn group rules

When the -fair_scheduler_allocation_path is configured with a policy that uses
the "primaryGroup" Yarn queue allocation rule, Yarn throws an error if the user
is not on the local OS. Currently the user will get an error message that says:
"java.io.IOException: No groups found for user <username>". We now return a more
helpful error message.

Change-Id: I014ac15ef607e473957752f23af94d0cc4efec0f
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2078
Reviewed-by: Matthew Jacobs <mj@cloudera.com>
Tested-by: jenkins