Complete JMS Publisher test suite

[kir-titievsky]

The plan is to

1. Take section 6 in [1]
2. port them over to Cloud Pub/Sub
3. Add tests for multiple subscription pattern, if applicable.

[1] https://github.com/skyscreamer/nevado/wiki/Master-Feature-Grid

[urshunkeler]

The Publisher test suite (this issue) is being implemented in the branch "jms_publisher_test_suite". The tests currently fail because of the following issues:

• Implement PubSubMessageConsumer class #65
• Implement PubSubTopic class #66
• Implement PubSubTopicConnection class #67
• Implement PubSubTopicSession class #68
• Create a TopicConnectionFactory #69
• Implement the createTopicConnection() method in the GeneralTopicTest #70

[urshunkeler]

The tests are now complete (with respect to the Nevado tests in section 6), they compile, but they do not fully work. This means that when a test fails, it might also be because the test is not properly implemented (see the TODOs in the source code).