Fix the code miss to show the correct error messages

In keystone/common/ldap/core.py I found the code like below:

 86 raise ValueError(_(
 87 'Invalid LDAP TLS certs option: %(option). '
 88 'Choose one of: %(options)s') % {

The code "%(option)" in line 87 should be fixed to "%(option)s" to
show the correct error messages when the exception happens.
This patch fixes this error.

Fixes bug #1220601

Change-Id: I87328080facd4d9b1349a677c00a93d118993538

keystone/common/ldap/core.py

@@ -84,7 +84,7 @@ def parse_tls_cert(opt):
         return LDAP_TLS_CERTS[opt]
     except KeyError:
         raise ValueError(_(
-            'Invalid LDAP TLS certs option: %(option). '
+            'Invalid LDAP TLS certs option: %(option)s. '
             'Choose one of: %(options)s') % {
                 'option': opt,
                 'options': ', '.join(LDAP_TLS_CERTS.keys())})