Travis: fix stalled build

[ricardopereira]

#143 - Use travis_wait when a long running command or compile step regularly takes longer than 10 minutes without producing any output. It writes a short line to the build log every minute for 20 minutes, extending the amount of time your command has to finish.

[ricardopereira]

It's working 😁

So, the test suite will only output the log when it's done.
If the test suite fails then the command will exit with error, like it used to be.
The summary of failures is generated by xcodebuild. One test failed with:

[11:38:08]: ▸ Failing tests:
[11:38:08]: ▸ -[RestClient RestClient__should_request_another_token_after_current_one_is_no_longer_valid()]
[11:38:08]: ▸ -[RealtimeClientConnection Connection__ACK_and_NACK__should_trigger_the_failure_callback_for_the_remaining_pending_messages_if__connection_is_closed()]
[11:38:08]: ▸ ** TEST FAILED **

[ricardopereira]

@mattheworiordan @tcard Can I merge?

[tcard]

Cool! LGTM

[mattheworiordan]

Nice :)