Change how post data is encoded to json in mlflow R client. (#947)
Change how post data is encoded to json in mlflow R client. (#947)

* Added support for basic rest authentication to mlflow R client. Added Support for reading databricks authentication info from config file and environment variables.

* Addressed review comments. Replaced caTools with base64enc.

* Added missing file from my previous commit.

* Adressed review comments.

* Addressed review comments.

* Renamed clazz to class.

* Pass data as list instead of json string to POST and set encode = 'json'.

* Turn data into string before generating json to avoid unintended conversions (e.g. long integers printed out in scientific notation.)

mlflow/mlflow,mlflow/mlflow,mlflow/mlflow,mlflow/mlflow,mlflow/mlflow,mlflow/mlflow,mlflow/mlflow