splitting out Unirest\File and updating README

src/Unirest/Request.php

@@ -173,19 +173,6 @@ class Request
         return self::send(Method::TRACE, $url, $body, $headers, $username, $password);
     }
 
-    /**
-     * Prepares a file for upload. To be used inside the parameters declaration for a request.
-     * @param string $path The file path
-     */
-    public static function file($filename, $mimetype = '', $postname = '')
-    {
-        if (function_exists('curl_file_create')) {
-            return curl_file_create($filename, $mimetype = '', $postname = '');
-        } else {
-            return sprintf('@%s;filename=%s;type=%s', $filename, $postname ?: basename($filename), $mimetype);
-        }
-    }
-
     /**
      * This function is useful for serializing multidimensional arrays, and avoid getting
      * the 'Array to string conversion' notice