Add CertificateType filtering support for Locate

This change updates Locate operation support in the PyKMIP server,
allowing users to filter objects based on the object's
Certificate Type. Unit tests and integration tests have
been added to test and verify the correctness of this feature.

Additionally, the Locate demo scripts have also been updated to
support Certificate Type filtering. Simply use the
"--certificate-type" flag to specify a Certificate Type
enumeration values for the Locate script to filter on.

kmip/demos/units/locate.py

@@ -41,6 +41,7 @@ if __name__ == '__main__':
     initial_dates = opts.initial_dates
     state = opts.state
     object_type = opts.object_type
+    certificate_type = opts.certificate_type
     cryptographic_algorithm = opts.cryptographic_algorithm
     cryptographic_length = opts.cryptographic_length
     cryptographic_usage_masks = opts.cryptographic_usage_masks
@@ -198,6 +199,27 @@ if __name__ == '__main__':
                 masks
             )
         )
+    if certificate_type:
+        certificate_type = getattr(
+            enums.CertificateType,
+            certificate_type,
+            None
+        )
+        if certificate_type:
+            attributes.append(
+                attribute_factory.create_attribute(
+                    enums.AttributeType.CERTIFICATE_TYPE,
+                    certificate_type
+                )
+            )
+        else:
+            logger.error(
+                "Invalid certificate type provided: {}".format(
+                    opts.certificate_type
+                )
+            )
+            client.close()
+            sys.exit(-8)
     if unique_identifier:
         attributes.append(
             attribute_factory.create_attribute(