Added Cache::forever method to cache something for five years.

Signed-off-by: Taylor Otwell <taylorotwell@gmail.com>

laravel/cache/drivers/driver.php

@@ -53,6 +53,18 @@ abstract protected function retrieve($key);
 	 */
 	abstract public function put($key, $value, $minutes);
 
+	/**
+	 * Write an item to the cache for five years.
+	 *
+	 * @param  string  $key
+	 * @param  mixed   $value
+	 * @return void
+	 */
+	public function forever($key, $value)
+	{
+		return $this->put($key, $value, 2628000);
+	}
+
 	/**
 	 * Get an item from the cache, or cache and return the default value.
 	 *