Added inverted FP16 Initializer
Added inverted FP16 Initializer

Summary: Added initializer which sets up the ParameterInfo object in the opposite format as the pFP16Initializer. This is needed for when the op requires the initialized blob to be FP32 but a FP16 copy of the weights is needed.

Reviewed By: wesolwsk

Differential Revision: D5840832

fbshipit-source-id: 439e87f41a1dbc58bf63a5c0e7f7fc4cb00b4d65

pietern/caffe2,davinwang/caffe2,sf-wind/caffe2,pietern/caffe2,davinwang/caffe2,xzturn/caffe2,sf-wind/caffe2,sf-wind/caffe2,Yangqing/caffe2,pietern/caffe2,Yangqing/caffe2,caffe2/caffe2,davinwang/caffe2,Yangqing/caffe2,sf-wind/caffe2,Yangqing/caffe2,sf-wind/caffe2,pietern/caffe2,davinwang/caffe2,Yangqing/caffe2,xzturn/caffe2,xzturn/caffe2,davinwang/caffe2,pietern/caffe2,xzturn/caffe2,xzturn/caffe2