Thin 3.0: Client lifecycle unit tests

Need to implement the following plan for unit tests in Java client:

• Make sure that address parsing from string is covered, if supported;
• A logic related to choosing an address for the initial connection should be isolated and covered by the unit tests;
• A logic related to choosing the next connectable address (if possible). Make sure round-robin is used from the random position chosen on the previous step;
• Make sure that the correct port is used by default, if not specified.