Flowdock default config should not select success by default

[batmat]

Because of https://github.com/jenkinsci/flowdock-plugin/blob/master/src/main/resources/com/flowdock/jenkins/FlowdockNotifier/config.jelly#L25 Flowdock notifier will by default notify when build is successful.

IMO, this is a bad idea both in term of general CI where you should consider success is the normal way, and only 'react' when something changes (say, fails). In the Flowdock specific case, like in emails btw, it results in flooding the flow inbox with "success" messages. And failure can easily go unseen.

Please change that behaviour. If you agree with the rationale above (i.e. reducing the noise), I can issue a PR very soon.

Thanks a lot