* Switch to scale and offset design from min and max for Quantization

* Remove offset and make the quantize ops a single o/p op

* move cpu QuantOps to core and create builders

* rebase to HEAD

* remove convbias and convbiasrelu ctors which take conv

* remove mistakenly added quantize.rst

* remove offset

* Compute scale, move quantization ops to experimental dir and some PR feedback

* Normalize license headers