Travis: Initiating build for commit '5f168c7acdd8f51a186c1c76fb79ce5aa3b199dd' on branch 'master': Prevent some random build failures when connectivity fails, by calling travis_retry which retries up to 3 times

https://travis-ci.org/piwik/piwik/jobs/23570274
https://travis-ci.org/piwik/piwik/jobs/23912462
http://blog.travis-ci.com/2013-05-20-network-timeouts-build-retries/