Fix an XSS in contributors/views.py
Fix an XSS in contributors/views.py

As a Proof of Concept consider a POST request to
https://pontoon.mozilla.org/save-custom-homepage/ with
the "custom_homepage" parameter set to "<script>evil_code</script>"

jotes/pontoon,mathjazz/pontoon,jotes/pontoon,mozilla/pontoon,mathjazz/pontoon,mozilla/pontoon,mozilla/pontoon,jotes/pontoon,mozilla/pontoon,mathjazz/pontoon,mathjazz/pontoon,mathjazz/pontoon,jotes/pontoon,mozilla/pontoon