saml_base must be a subpath of saml_auth in client installer
    
    If the authenticated path doesn't reside under saml_base (which
    defaults to /) then mod_auth_mellon can't find the IdP.
    
    https://fedorahosted.org/ipsilon/ticket/163
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewd-by: Patrick Uiterwijk <puiterwijk@redhat.com>