The Hamas has definitely committed war crimes. There's no debate on that. It is less clearly obvious (in the legal sense) that Israel did. I think that there's a fair chance they did - but it's not really their hallmark, as is with Hamas.
Tossing terms about is great, but misleading. Crimes against humanity and war crimes are not exactly the same thing. War crimes, I think, are more prevalent, in general. For example, the Hamas attack sans the atrocities committed, would be a war crime. If the atrocities are included, it's probably in the category of crimes against humanity.
You can keep calling things 'war crimes' but that doesn't make them so. That war is ugly, and many bad things happen doesn't mean all of them are legally forbidden.