build: Disable release builds on Travis
build: Disable release builds on Travis

Release builds were failing due to OOM on Travis. Disable for now.

broadinstitute/firepony,NVlabs/firepony,broadinstitute/firepony,NVlabs/firepony,NVlabs/firepony,NVlabs/firepony,broadinstitute/firepony,broadinstitute/firepony