Caper

* thread safe inter-storage file transfer
- added a simple spin lock (with `.lock` file) to obtain thread safety for file transfer
- multiple users can share the same `tmp-dir`, `tmp-s3-bucket` and `tmp-gs-bucket`.
- limitation
- possible race condition
- skip copying only if file size of source and target files are same (does not check md5sum)
- source files are not locked to prevent deadlock
- make sure that source files are almost like read-only

* 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](https://github.com/broadinstitute/cromwell/issues/4364) on aws)

* Bug fix for singularity in slurm backend (task hanging issue)

* Show more information (even successfully completed tasks if `--show-completed-task` is given) for `caper troubleshoot`
- JOB_ID: PID or JOB_ID (SLURM or SGE) of JOB
- RUN_START: start datetime if task is run
- RUN_END: end datetime if task is run

* added `--use-netrc` to use `~/.netrc` file to handle HTTP username/password more securely

* Bug fix for `--file-db` for Caper server when it's defined in cmd line args