investigate hhvm build failure

[dbu]

investigate why hhvm builds fail and fix them. we started ignoring the fail in #11

[xabbuh]

Looks like failures are triggered by Puli.

[sagikazarmark]

Confirmed, puli does not support HHVM ATM: https://github.com/puli/cli/blob/master/.travis.yml#L22

[Nyholm]

Puli is no longer a dependency to this bundle. We should consider rewrite our tests so they are not dependent of Puli.