Added logging to SiteTheme.get_theme
Added logging to SiteTheme.get_theme

This will help us debug an issue with theming.

LEARNER-3079

edx/ecommerce,eduNEXT/edunext-ecommerce,eduNEXT/edunext-ecommerce,eduNEXT/edunext-ecommerce,edx/ecommerce,edx/ecommerce,edx/ecommerce,eduNEXT/edunext-ecommerce