Doesn't look to me like this can work with web-based AD, so it's probably useless unless you have an actual domain controller on-premises.

For the record, web-based 365 ADs (and most modern on-prem) already support webservices, just soap (and somewhat painful) rather than rest. I use it to authenticate from an app outside our network, the implementation wasn't that hard (python) but i really only do auth, no manipulation. It would be cool if MS added REST as an option to make this sort of common case easier, but they are too busy selling you complex integrated services to do that in Azure ("use Visual Studio, next next next, your app is now deployed on Azure and completely integrated with all these management tools. Cool, uh? Now give me lots of money every month or turn it off.")