updating gcloud command on travis (#2248)
updating gcloud command on travis (#2248)

they seem to have changed the gcloud cli to use --key-file instead of
--key in authentication
broadinstitute/hellbender,broadinstitute/hellbender,ksthesis/gatk,magicDGS/gatk,ksthesis/gatk,broadinstitute/hellbender,ksthesis/gatk,frank-y-liu/gatk,broadinstitute/hellbender,magicDGS/gatk,ksthesis/gatk,broadinstitute/hellbender,frank-y-liu/gatk,frank-y-liu/gatk,frank-y-liu/gatk,magicDGS/gatk,magicDGS/gatk,frank-y-liu/gatk,ksthesis/gatk,magicDGS/gatk,frank-y-liu/gatk,magicDGS/gatk,broadinstitute/hellbender,ksthesis/gatk