Upgrade to vs2015 for native projects.

Upgrade to vs2015 for native projects.

* Upgraded all projects to new vs2015 tool chain.
* Used mono.props through property manager instead of import.
* Fixed dependencies to be more explicitly in additional dependecies.
* Fixed error in mono.props, switched $ to % when referencing internal variables.
* Added property variables for includes and libraries, defined in mono.props.