Allowing Travis CI Failures for HHVM
Allowing Travis CI Failures for HHVM

Sadly, Travis CI pulls HHVM 3.6.6 for its build, directly from the distro. As can be seen here, https://github.com/facebook/hhvm/commit/5bd38ecd5482e933be27417e050a280c9c3f3aeb#diff-60d29ccbc84f4563554014aa69f57d73 , the use of `ARRAY_FILTER_USE_KEY` was not introduced in HHVM until a later version. This is causing the build to fail, which isn't critical to the project

improvframework/configuration