Use a group photo of the ambassadors as a header image

We don't have permission to use the old header image.

Author: mitio

img/codeweek-ambassadors-2015.jpg

@@ -6,7 +6,7 @@
 
 	<div class="swiper-container swiper-parent">
 		<div class="swiper-wrapper">
-			<div class="swiper-slide dark" style="background-image: url('img/portada.jpg');">
+			<div class="swiper-slide dark" style="background-image: url('img/codeweek-ambassadors-2015.jpg');">
 				<div class="container clearfix">
 					<div class="slider-caption slider-caption-center">
 						<div id="countdown-ex1" class="countdown countdown-large coming-soon divcenter bottommargin" style="max-width:700px;"></div>