Fixed curl error. Edited code so it takes  argument into consideration

I was gettin curl error saying it will only take 2 as an argument for curl_setopt. 
Also i needed weather report for 5 days but as it stands it is not possible since it always returns only current conditions, so I changed code, but functionality is unchanged.
methods you described earlier still work with no change, but you can now also call method 
`$WorldWeatherOnline::get_weather($location, $days = 1, $format = 'json')`