* Set default to `vs2015` since `vs2017` is not CI-green yet
* changes vcbuild.bat arg from `vc2015` to `vs2015`/`vs2017`
`vc` as in Visual C++ is actually versions 14.0 or 14.10
`vs` as in Visual Studio is 2015 or 2017
Ref: http://lists.boost.org/Archives/boost/2017/03/233597.php🤦
* keep `vc2015` for backward compatibility but "undocumented"
* tools: transplant vswhere wrapper from `msvs-com-helper`
Ref: https://github.com/node4good/msvs-com-helper
PR-URL: https://github.com/nodejs/node/pull/11852
Reviewed-By: João Reis <reis@janeasystems.com>
Reviewed-By: Bartosz Sosnowski <bartosz@janeasystems.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Refael Ackermann