common/test_sender: Update test for perform_request
common/test_sender: Update test for perform_request

* Add test_perform_request_req_type_put
* Updated test_perform_request_req_type_post
  * Now tests the default case

Change-Id: Iff7bc4d4370c5517e481db15ae1318f2e4fd34a5

openstack/collectd-ceilometer-plugin,openstack/collectd-ceilometer-plugin