[CB-4929] plugin-splashscreen not loading proxy windows8

(cherry picked from commit 71a8c9cc33e54ceb9cbaadd642717b9c297d7242)
[CB-4934] plugin-splashscreen should not show by default on Windows8

(cherry picked from commit 2dc0f42b8f7779ba0cac5778a879aaf0162bf579)