This enables the use of the SharePoint webdav endpoint provided by
OneDrive for Business or Office365 Education Accounts. It enables
unverified accounts to be accessed with rclone via webdav as it isn't
possible through the normal onedrive backend.
This integrates the https://github.com/hensur/onedrive-cookie-test
package to fetch the required cookies to authorize against the
SharePoint webdav endpoint.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.
The new code layout is documented in CONTRIBUTING.
