Little mistake

[raffobaffo]

Hello, thanks for your time spent doing this .
I'm doing some tests since yesterday, and today I came across a little problem while I was trying to use deleteFaces() function.
On line 156 of Rekognition.php, there's a mistake in how the $faceIds parameter is sent to Rekognition: it should be "FaceIds" but instead there's "FacesIds". This results in a missing required field error.

I'm not using it, but I do believe also deleteFacesAsync will have same problem.