Mlflow

Breaking changes:

- [Projects] Removed the `use_temp_cwd` argument to `mlflow.projects.run()`
(`--new-dir` flag in the `mlflow run` CLI). Runs of local projects now use the local project
directory as their working directory. Git projects are still fetched into temporary directories
(215, smurching)
- [Tracking] GCS artifact storage is now a pluggable dependency (no longer installed by default).
To enable GCS support, install `google-cloud-storage` on both the client and tracking server via pip.
(202, smurching)
- [Tracking] Clients running MLflow 0.4.0 and above require a server running MLflow 0.4.0
or above, due to a fix that ensures clients no longer double-serialize JSON into strings when
sending data to the server (200, aarondav). However, the MLflow 0.4.0 server remains
backwards-compatible with older clients (216, aarondav)

Features:

- [Examples] Add a more advanced tracking example: using MLflow with PyTorch and TensorBoard (203)
- [Models] H2O model support (170, ToonKBC)
- [Projects] Support for running projects in subdirectories of Git repos (153, juntai-zheng)
- [SageMaker] Support for specifying a compute specification when deploying to SageMaker (185, dbczumar)
- [Server] Added --static-prefix option to serve UI from a specified prefix to MLflow UI and server (116, andrewmchen)
- [Tracking] Azure blob storage support for artifacts (206, mateiz)
- [Tracking] Add support for Databricks-backed RestStore (200, aarondav)
- [UI] Enable productionizing frontend by adding CSRF support (199, aarondav)
- [UI] Update metric and parameter filters to let users control column order (186, mateiz)

Bug fixes:

- Fixed incompatible file structure returned by GCSArtifactRepository (173, jakeret)
- Fixed metric values going out of order on x axis (204, mateiz)
- Fixed occasional hanging behavior when using the projects.run API (193, smurching)

- Miscellaneous bug and documentation fixes from aarondav, andrewmchen, arinto, jakeret, mateiz, smurching, stbof

Breaking changes:

- [MLflow Server] Renamed `--artifact-root` parameter to `--default-artifact-root` in `mlflow server` to better reflect its purpose (165, aarondav)

Features:

- Spark MLlib integration: we now support logging SparkML Models directly in the log_model API, model format, and serving APIs (72, tomasatdatabricks)
- Google Cloud Storage is now supported as an artifact storage root (152, bnekolny)
- Support asychronous/parallel execution of MLflow runs (82, smurching)
- [SageMaker] Support for deleting, updating applications deployed via SageMaker (145, dbczumar)
- [SageMaker] Pushing the MLflow SageMaker container now includes the MLflow version that it was published with (124, sueann)
- [SageMaker] Simplify parameters to SageMaker deploy by providing sane defaults (126, sueann)
- [UI] One-element metrics are now displayed as a bar char (118, cryptexis)

Bug fixes:

- Require gitpython>=2.1.0 (98, aarondav)
- Fixed TensorFlow model loading so that columns match the output names of the exported model (94, smurching)
- Fix SparkUDF when number of columns >= 10 (97, aarondav)
- Miscellaneous bug and documentation fixes from emres, dmatrix, stbof, gsganden, dennyglee, anabranch, mikehuston, andrewmchen, juntai-zheng

This is a patch release fixing some smaller issues after the 0.2.0 release.

- Switch protobuf implementation to C, fixing a bug related to tensorflow/mlflow import ordering (issues 33 and 77, PR 74, andrewmchen)
- Enable running mlflow server without git binary installed (90, aarondav)
- Fix Spark UDF support when running on multi-node clusters (92, aarondav)

- Added `mlflow server` to provide a remote tracking server. This is akin to `mlflow ui` with new options:

- `--host` to allow binding to any ports (27, mdagost)
- `--artifact-root` to allow storing artifacts at a remote location, S3 only right now (78, mateiz)
- Server now runs behind gunicorn to allow concurrent requests to be made (61, mateiz)

- TensorFlow integration: we now support logging TensorFlow Models directly in the log_model API, model format, and serving APIs (28, juntai-zheng)
- Added `experiments.list_experiments` as part of experiments API (37, mparkhe)
- Improved support for unicode strings (79, smurching)
- Diabetes progression example dataset and training code (56, dennyglee)
- Miscellaneous bug and documentation fixes from Jeffwan, yupbank, ndjido, xueyumusic, manugarri, tomasatdatabricks, stbof, andyk, andrewmchen, jakeret, 0wu, aarondav

- Initial version of mlflow.