Added .travis.yml to get travis-ci to build and run tests for us.
In addition this fixes a flaky test due to the fact that when lightning2
connects to lightning3 and we tell lightning3 to restart, then
lightning2 will back-off its reconnection attempts, potentially causing
a timeout to trigger during tests. This was triggered by travis-ci
relatively consistently since the restart would take quite some
time. Now simply restarting them in reverse order and a small timeout
seems to fix this consistently.
