Config for php gd extension

Dockerfile

@@ -11,6 +11,7 @@ RUN apt-get update && apt-get install -y \
         mysql-client
 
 # Elgg requirements
+RUN docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/
 RUN docker-php-ext-install pdo pdo_mysql mysql
 RUN docker-php-ext-install mbstring gd