Add png signs

signs_png/37c3-locations-cert-cert-left.png

signs_png/37c3-locations-cert-cert-only-on-red-paper.png

signs_png/37c3-locations-cert-cert-only.png

signs_png/37c3-locations-cert-cert-right.png

signs_png/37c3-locations-cert-mask.png

signs_png/37c3-locations-cert-no-passage.png

signs_png/37c3-locations-cert-patient-only.png

signs_png/37c3-locations-engelkueche-angel-kitchen.png

signs_png/37c3-locations-engelkueche-dishwashing-kitchen.png

signs_png/37c3-locations-hackertours-qr.png

signs_png/37c3-locations-kidsspace-kinderwagenparkplatz.png

...c3-locations-schilderhalter-1-og-c3sign-chaospatinnen.png

...ons-schilderhalter-1-og-c3sign-hall-turn-around-noten.png

...locations-schilderhalter-1-og-c3sign-hall-turn-around.png

...ng/37c3-locations-schilderhalter-1-og-c3sign-kidspace.png

...37c3-locations-schilderhalter-1-og-c3sign-photopolicy.png

...halter-1-og-c3sign-speakersdesk-eventphone-gsm-heaven.png

...7c3-locations-schilderhalter-1-og-c3sign-you-are-here.png

...locations-schilderhalter-1-og-foyer-abc-hall-g-no-way.png

...3-locations-schilderhalter-1-og-foyer-abc-no-way-left.png