v0.2.8

• Added --max-retries (default:1) to retry failing tasks
• Replaced deprecated actor factory for google backend
• Cromwell server submits jobs slowly (1 per 2 second) due to possible socket error for SLURM/other cluster engines.
• Bug fix for aws backend (typo in code: out_aws_bucket->out_s3_bucket)
• Upgrade cromwell 40 to 42 (to fix aliased task isolation issue on aws)