run ./gradlew test without test forks on travis
run ./gradlew test without test forks on travis

to reduce load and prevent exit status 137
https://travis-ci.org/crate/crate/jobs/160142842#L1682
https://discuss.gradle.org/t/gradle-check-fails-but-tests-finish-with-success/10214

EvilMcJerkface/crate,crate/crate,crate/crate,crate/crate,EvilMcJerkface/crate,EvilMcJerkface/crate