added help text for X509_CERT_DIR to grid-default-ca error message.
added help text for X509_CERT_DIR to grid-default-ca error message.

globus/globus-toolkit,globus/globus-toolkit,globus/globus-toolkit,ellert/globus-toolkit,globus/globus-toolkit,globus/globus-toolkit,ellert/globus-toolkit,ellert/globus-toolkit,gridcf/gct,globus/globus-toolkit,globus/globus-toolkit,gridcf/gct,gridcf/gct,ellert/globus-toolkit,ellert/globus-toolkit,gridcf/gct,ellert/globus-toolkit,ellert/globus-toolkit,gridcf/gct,gridcf/gct,globus/globus-toolkit,ellert/globus-toolkit