add OpenSSH plugin

lemur/plugins/lemur_openssh/plugin.py

@@ -109,10 +109,11 @@ class OpenSSHIssuerPlugin(CryptographyIssuerPlugin):
         ).decode()
         public_key += ' ' + cert['user']['email']
         # sign it with authority private key
-        if 'root_authority' in cert:
-            root_authority = cert['root_authority']
+        if 'root_authority' in cert and cert['root_authority']:
+            authority = cert['root_authority']
         else:
-            root_authority = get_by_root_authority(cert['authority']['id'])
+            authority = cert['authority']
+        root_authority = get_by_root_authority(authority['id'])
         authority_private_key = root_authority.private_key
         cert['body'] = sign_certificate(
             cert['common_name'],