Log the command output on CertificateConfigError

In auth_token middleware if the CertificateConfigError is raise for a reason
other than the certificate file missing or the ca cert file missing, log the
actual output from the verify comment to aid in correcting the issue.

Related-Bug: #1285833
Change-Id: I6b469b9037b7ef59993132f87a75152149ee6310

keystoneclient/middleware/auth_token.py

@@ -1259,6 +1259,7 @@ class AuthProtocol(object):
                                           self.signing_ca_file_name):
                     self.fetch_ca_cert()
                     continue
+                self.LOG.error('CMS Verify output: %s', err.output)
                 raise
             except cms.subprocess.CalledProcessError as err:
                 self.LOG.warning('Verify error: %s', err)