Rename variable

[ErickZH]

Rename variable $_map to $_data

I know it's a minor change but it's something that is driving me crazy...

This change is sent by the docblock of the Jsonq class construct.

    /**
     * this constructor set main json file path
     * otherwise create it and read file contents
     * and decode as an array and store it in $this->_data
     *
     * @param null $jsonFile
     * @throws Exceptions\FileNotFoundException
     * @throws InvalidJsonException
     */
    public function __construct($jsonFile = null)