Add support for Azure Storage in xbcloud

Currently xbcloud supports S3 and Google cloud. It would be nice to have support for Azure storage as well.

Add below new option for uploading backup to azure using REST API.
--azure-storage-account=name
AZURE storage account
--azure-container-name=name
AZURE container name
--azure-access-key=name
AZURE access key
--azure-endpoint=name
AZURE cloud storage endpoint
--azure-tier-class=name
Azure cloud tier class. Hot|Cool|Archive

Also for usablity user can add these option as Environment variables .

To run against azure development storage (azurite)
option --azure-development-storage is added. It uses the default access_key
and storage account of azurite and testcontainer for container which
can be overwritten with above options.

Also in 2.4 backported support for s3 storage class from 8.0