Ignore alreadyExist error in usermanager
Ignore alreadyExist error in usermanager

Problem:
CreateNewUserClusterRoleBinding attempts to create the role and binding
for a user, under a race this can error and return an alreadyExists

Solution:
Ignore alreadyExists errors here and continue

cjellick/rancher,cjellick/rancher,rancher/rancher,rancher/rancher,rancher/rancher,cjellick/rancher,rancherio/rancher,rancherio/rancher,rancher/rancher