BAU: Added PNG version of Verify logo
BAU: Added PNG version of Verify logo

IE8 does not support SVG, so adding a failover to PNG

Author: da39a3ee5e6b4b0d3255bfef95601890afd80709@jakubmiarka

alphagov/verify-frontend,alphagov/verify-frontend,alphagov/verify-frontend,alphagov/verify-frontend