More test case for arguments of methods

[ykokw]

current test code looks to comfirm only response parsing

For example, in test_niftycloud.py

	# create success
	def test_create_instance_success(self):
		with mock.patch('requests.post', self.mockRequestsPostRunInstance):
			with mock.patch('niftycloud.get_instance_state', self.mockGetInstanceState16):
				self.assertEqual(
					(True, 16, 'created'),
					niftycloud.create_instance(self.mockModule)
				)

test code of create_instance method not confirm following things

• Is it really pass arguments to requests.post method for API authentication (e.g. signature) ?
• Is it validate arguments for create instances?

I think it should be separate test case in accordance to test purpose