Added methods to use Sistrix API

Fixes issue #88.

If my other PR is merged, you can cherrypick the relevant commits from this PR. Thanks!
you error was "Undefined offset: 0"
right here we need the ```isset($matches[1][0])```

but we can write it better

```php
if (isset($matches[1][0])) {
   return parent::noDataDefaultValue();
}
return str_replace(',','.',$matches[1][0]);

```