Added test for CudaTensor.{mean,var,std}

Two tests (the dimension-wise means) currently fail.
Added single-dimensional CudaTorch.mean

i.e. the form
	y = torch.mean(x, dim)
Fixed documentation for torch.var
add custom gnuplot style string option,
add ability to pass in multi-column data
Merge branch 'master' of github.com:andresy/torch
Merge pull request #143 from akfidjeland/cuda-mean

Cuda mean