Implementation of secure param for PageUrlAnnotation

There are a few things I am not 100% sure:
- should `$secure` always overwrite the protocol? even if it is not present.
- introduce `$secure` property and getter? Just now I alter the protocol to the current passed value of `$secure`
- comments of the new `$secure` param, quite a lot of information for a single line

Closes #63.
Look at https://scrutinizer-ci.com/g/aik099/qa-tools/inspections/efaece7c-8801-4394-9065-141fa385558c/issues/files/library/aik099/QATools/PageObject/PageFactory.php?status=new&orderField=path&order=asc&issueId=247bdcd2-2b3a-4e1a-af41-00ce0f74390d

I wasn't able to understand what it means at first, but then I got it:

1. few lines above we have this code `$this->config = isset($config) ? $config : new Config();`
2. and `$config = null` by default from constructor
3. so you should use `$this->config->getOption` or otherwise you'll be operating on NULL when no config is given

And no test covers that. Better to test factory creation without a provided config object.