CB-8637 add windows to plugman
CB-8637 add windows to plugman

Fixes error when trying to add plugin for platform windows using plugman
directly.

corimf/cordova-plugman,phonegap-build/cordova-plugman,apache/cordova-plugman,Icenium/cordova-plugman,e2l3n/cordova-plugman,tripodsan/cordova-plugman