Adds self-update for composer to hopefully fix travis timeout
Allow dev-master builds to fail

Symfony dev-master may be uninstallable due to stability issues with the
dependencies. So it's ok for dev-master to fail as long as the stable
releases are fine.
Merge pull request #78 from Flagbit/fix-travis

Fix travis
Increment response listener priority in order to avoid New Relic transactions with false application name