Login: Edit WPAuth to allow host app to configure nav bar logo #146
Description
As a user, I want to see the Woo logo in the navigation bar when I am logging into the app.
Android already has this feature, so we should try to keep parity: woocommerce/woocommerce-android#126 (comment)
Current: http://cld.wthms.co/HChmix
Example: http://cld.wthms.co/kVdK5e