Enforce string for _METHOD
Enforce string for _METHOD

As this could have come from SimpleXML, cast to a string.

mnapoli/Slim,juliangut/Slim,AndrewCarterUK/Slim,slimphp/Slim,RealSelf/Slim,Sam-Burns/Slim,feryardiant/slim,iinux/Slim,iinux/Slim,JoeBengalen/Slim,akrabat/Slim,dopesong/Slim,iinux/Slim,foxyantho/Slim