function heNormal(args) {
	  return new HeNormal(args);
	}
He normal initializer.

It draws samples from a truncated normal distribution centered on 0
with `stddev = sqrt(2 / fanIn)`
where `fanIn` is the number of input units in the weight tensor.

Reference:
    He et al., http://arxiv.org/abs/1502.01852

@doc {heading: 'Initializers', namespace: 'initializers'}