The function calculates the activation and the output from the sigmoid
transfer function. It returns a binary matrix where a entry is 1 if the value
is bigger than a random number generated with runif.
binSigmoidUnit(data, weights)The data matrix for the calculation
The weight and bias matrix for the calculation
A list with the binary activation of the unit in the first entry.
Other DArch unit functions: linearUnitDerivative;
  linearUnit;
  maxoutUnitDerivative;
  sigmoidUnitDerivative;
  sigmoidUnit;
  softmaxUnitDerivative;
  softmaxUnit;
  tanSigmoidUnitDerivative;
  tanSigmoidUnit