[tune] Initial Commit for Tune CLI (#3983)

This introduces a light CLI for Tune.

python/ray/tune/scripts.py

@@ -0,0 +1,43 @@
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import click
+import ray.tune.commands as commands
+
+
+@click.group()
+def cli():
+    pass
+
+
+@cli.command()
+@click.argument("experiment_path", required=True, type=str)
+@click.option(
+    '--sort', default=None, type=str, help='Select which column to sort on.')
+def list_trials(experiment_path, sort):
+    """Lists trials in the directory subtree starting at the given path."""
+    commands.list_trials(experiment_path, sort)
+
+
+@cli.command()
+@click.argument("project_path", required=True, type=str)
+@click.option(
+    '--sort', default=None, type=str, help='Select which column to sort on.')
+def list_experiments(project_path, sort):
+    """Lists experiments in the directory subtree."""
+    commands.list_experiments(project_path, sort)
+
+
+cli.add_command(list_trials, name="ls")
+cli.add_command(list_trials, name="list-trials")
+cli.add_command(list_experiments, name="lsx")
+cli.add_command(list_experiments, name="list-experiments")
+
+
+def main():
+    return cli()
+
+
+if __name__ == "__main__":
+    main()