Dsub

This release includes:

- `google-v2` provider:
- Support for `--network`, `--cpu-platform`, `--timeout` parameters
- Add events to dstat.list for google V2 provider
- Using `--min-cores` or `--min-ram` now directs users to `--machine-type`

- Add Finland and Los Angeles regions and new Singapore zone.
- Various test suite improvements

Note that this release includes an important change to the way that log file names are formatted for `dsub` jobs that use `--retries`. The `task-attempt` is now automatically included in the log file name such that logs for each attempt do not overwrite the previous attempt.

All unit and integration tests now pass for the `google-v2` provider.
Users interested in [Google's Pipelines v2](https://cloud.google.com/genomics/reference/rest/v2alpha1/pipelines) are encouraged to give it a try.

This release includes:

* `google-v2` provider:
* `dstat` fields such as `envs`, `inputs`, `outputs`, and `logging` now supported.
* `ddel` supported

* General
* `dsub` returns task-id even if failure is detected when using `--wait`.
* `events` included in `dstat` output (`local` and `google` providers)

This release includes:

* Initial support of `dsub` automatic retries
* `dstat` support for the `--summary` flag, providing a more compact output for `--tasks` jobs
* Provider improvements
* Local provider
* Use parallel copy for localizing and de-localizing files
* Deterministic `dstat` response ordering
* Google-v2 provider (still in progress)
* File localization/delocalization
* v2alpha1 timestamp format support
* Various test suite fixes

This release includes incremental progress on the Google Genomics Pipelines v2 provider and general refactoring to enable this upcoming feature.

Other user visible changes include:

* Support for empty `--inputs` and `--outputs` from the command line and task files.
* `dstat` now includes provider attributes, such as compute zone and machine type.

This release includes new documentation, bug fixes, and test optimizations. A highlight of the release is the Split and Process demo contributed by JP. In addition the following new features and bug fixes are present.

* Support for europe-west4 and northamerica-northeast1 regions
* Add support for empty environmental variables
* Require Python 2 during install
* Multiple test optimizations.

- Allow use of `--skip` and `--tasks` flags
- Fix rare edge case causing incorrect ordering of jobs returned from dstat
- Allow specification of upper-bound for job create-time
- A number of small updates to the (still experimental) Python API