0.8.4

• The issue of auto-determined EBS size being sometimes not an integer fixed.
• Now input files in the unicorn input json can be written in the format of s3://bucket/key instead of {'bucket_name': bucket, 'object_key': key}
• command can be written in the format of a list for aesthetic purpose (e.g. [command1, command2, command3] is equivalent to command1; command2; command3)