Change some images, add credits and handle them

images/CREDITS.md

@@ -1,2 +1,6 @@
 - snow.png (Public domain): Gareth Patterson => https://www.flickr.com/photos/gareth_patterson/6858690131/
 - clouds.png (Public domain): Joe deSousa => https://www.flickr.com/photos/mustangjoe/14639363196/
+- thunderstorm.png (Public domain): Matthew Eaton => https://www.flickr.com/photos/matthew_eaton/13881379074/in/photostream/
+- sun.png (CC by 2.0): Shanna S => https://www.flickr.com/photos/pineappleandcoconut/16265018786/
+- rain.jpg (Public domain): George Hodan => http://www.publicdomainpictures.net/view-image.php?image=23191&picture=pluie
+- mist.png (CC by SA 2.0): Montgomery County Plan => https://www.flickr.com/photos/75012107@N05/8609938706/

js/public/app.js

@@ -32,9 +32,12 @@ app.controller('WeatherController', ['$scope', '$interval', '$timeout', '$compil
 		$scope.currentCity = null;
 
 		$scope.imageMapper = {
-			"Clear": "sun_clear.jpg",
-			"Clouds": "clouds.jpg",
+			"Clear": "sun.png",
+			"Clouds": "clouds.png",
+			"Mist": "mist.png",
 			"Rain": "rain.jpg",
+			"Snow": "snow.png",
+			"Thunderstorm": "thunderstorm.png",
 		}
 
 		$timeout(function () {