Revert "changes favicon to a shield."
Revert "changes favicon to a shield."

This reverts commit 35c2345c733b29e575062579141b3e48b375ab82.

mpurzynski/MozDef,mozilla/MozDef,mozilla/MozDef,mozilla/MozDef,mozilla/MozDef,jeffbryner/MozDef,mpurzynski/MozDef,jeffbryner/MozDef,mpurzynski/MozDef,jeffbryner/MozDef,jeffbryner/MozDef,mpurzynski/MozDef