Add place service

[TeLiXj]

I have created the add place service described [here] (https://developers.google.com/places/web-service/add-place). For this I've changed AbstractService.php and AbstractHttpService.php to support POST requests. I've tryed to use your code style as much as I was could, like for example using other services or docs as a base to develop this service. I've created docs too with info extracted from the Google Maps API page.

I'll create delete place service in the future and this afternoon I hope create a pull request on Ivory Google Maps Bundle to use the new add place service described here.

I hope that you like my work :)