Change download() to not overwrite files by default

[capjamesg]

Description

This PR changes the download() method to set the overwrite flag to False by default. This will ensure that a dataset is not re-downloaded every time the download() method is run.

This addresses #108.

Type of change

• New feature (non-breaking change which adds functionality)

How has this change been tested, please provide a testcase or example of how you tested the change?

Run the following snippet twice:

!pip install roboflow

from roboflow import Roboflow
rf = Roboflow(api_key="")
project = rf.workspace("capjamesg").project("streamlit-logo-detection")
dataset = project.version(1).download("coco")

When you run the code for the first time, a Downloading Dataset Version Zip in message should appear as the dataset is downloaded. On the second run, Downloading Dataset Version Zip in should not appear.

Any specific deployment considerations

N/A

Docs

N/A

[tonylampada]

lgtm