VS: Add source file property to specify Windows App deployment location

Add a VS_DEPLOYMENT_LOCATION source file property to specify where to
put files that are part of the package.  For example:

  set_property(SOURCE ${ASSET_FILES} PROPERTY VS_DEPLOYMENT_LOCATION "assets")

Without this, sources marked with VS_DEPLOYMENT_CONTENT cannot be
located properly.
Merge branch 'vs-phone-store-deployment-location' into release