Add Exif extension to composer.json

Author: Bartłomiej Kiełbasa

composer.json

@@ -13,7 +13,8 @@
     ],
     "require": {
         "php": ">=5.3.0",
-        "ext-gd": "*"
+        "ext-gd": "*",
+        "ext-exif": "*"
     },
     "autoload": {
         "classmap": ["src"]