`delete-bucket` command

[simonw]

I already have delete-user - this would be a similar utility but for deleting buckets. Mainly so I don't have to remember how to do it with awscli.

[simonw]

A already wrote some code for doing this in a test here:

s3-credentials/tests/test_integration.py

Lines 162 to 174 in 56cf379

	# Delete any buckets beginning s3-credentials-tests.
	buckets = json.loads(get_output("list-buckets", "--array"))
	buckets_to_delete = [
	bucket["Name"]
	for bucket in buckets
	if bucket["Name"].startswith("s3-credentials-tests.")
	]
	for bucket in buckets_to_delete:
	print("Deleting bucket: {}".format(bucket))
	# Delete all objects in the bucket
	boto3.resource("s3").Bucket(bucket).objects.all().delete()
	# Delete the bucket
	s3.delete_bucket(Bucket=bucket)

[mileswwatkins]

This addition to the CLI would be much appreciated, whether as a new subcommand or alternatively as part of the delete-user subcommand (as a --delete-bucket flag, paralleling the s3-credentials create BUCKET_NAME --create-bucket pattern). Thanks for developing s3-credentials!