Put back unregister for the publisher and clarify the reconnect behavior
of the test case. The exponential backoff of the client causes hard to
understand timing of the events.

All specs passed locally on hydro:

SUMMARY
 * RESULT: SUCCESS
 * TESTS: 103
 * ERRORS: 0
 * FAILURES: 0
Update .travis.yml and package.xml for rosbridge_library tests
Merge pull request #112 from syrnick/fix_all_tests

Fix all tests