Microsoft's Visual Studio Online (VSO) - http://www.visualstudio.com/products/what-is-visual-studio-online-vs - provides cloud-hosted source code repositories using Git or Team Foundation Version Control (TFVC). Please consider adding support for (at least) Git repositories hosted in VSO.

A REST API is available (documented at http://www.visualstudio.com/en-us/integrate/reference/reference-vso-overview-vsi.aspx) which provides access to Git commits and Service hooks are available to listen for issue key references. Authorisation is via OAuth 2.0 (see http://www.visualstudio.com/integrate/get-started/get-started-auth-oauth2-vsi).