supported protocols:
1. http(s)
2. s3 compatible with the env AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY,
   AWS_ENDPOINT_URL

Since the image kfserving/storage-initializer is big(~341MB) and have
some limits with http server, the end image size is 54.7MB:
1. support to download more than one uri
2. smaller image size: use minio-client instead of boto3(less than
40MB), remove gcs/azure
3. remove the http-server content-type limits
4. add obs protocol
5. also extract .tar.gz/.zip for s3
6. fix pep8 style

Signed-off-by: llhuii <liulinghui@huawei.com>