Create gh-pages branch for API documentation

[ivanlanin]

@Progi1984 I suggest that we create a gh-pages branch as outlined in this page. This will create http://phpoffice.github.io/PHPWord. I suggest that we use this URL to document our API. Here's an example: http://ivanlanin.github.io/PHPWord/api/

Thanks

[ivanlanin]

Hi @Progi1984, our docblock documentation is now good enough to be processed by phpdoc or apigen.

[Progi1984]

@ivanlanin I try this week or the next week, max ;)