Add more information for InvalidCredentials exception
Add more information for InvalidCredentials exception

This commit adds more information for the InvalidCredentials
exception. When users face these errors, these additional information
could be useful to resolve and investigate the issue.

Change-Id: I59c9ccdfcbb361df9d52ef9703245aaf11c693a2

openstack/tempest,masayukig/tempest,cisco-openstack/tempest,openstack/tempest,masayukig/tempest,cisco-openstack/tempest