Added dotenv component to define env vars in local file

src/Factory/CacheFactory.php

@@ -0,0 +1,30 @@
+<?php
+namespace Acelaya\UrlShortener\Factory;
+
+use Doctrine\Common\Cache\ApcuCache;
+use Doctrine\Common\Cache\ArrayCache;
+use Interop\Container\ContainerInterface;
+use Interop\Container\Exception\ContainerException;
+use Zend\ServiceManager\Exception\ServiceNotCreatedException;
+use Zend\ServiceManager\Exception\ServiceNotFoundException;
+use Zend\ServiceManager\Factory\FactoryInterface;
+
+class CacheFactory implements FactoryInterface
+{
+    /**
+     * Create an object
+     *
+     * @param  ContainerInterface $container
+     * @param  string $requestedName
+     * @param  null|array $options
+     * @return object
+     * @throws ServiceNotFoundException if unable to resolve the service.
+     * @throws ServiceNotCreatedException if an exception is raised when
+     *     creating a service.
+     * @throws ContainerException if any other error occurs
+     */
+    public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
+    {
+        return getenv('APP_ENV') === 'pro' ? new ApcuCache() : new ArrayCache();
+    }
+}