compile function not working in case of Conv layers.

[ayush1999]

FluxJS.compile() doesn't seem to work when Convolution layers are involved:

>>> using Flux
>>> using FluxJS
>>> m = Chain(
         Conv((2,2), 1=>16, relu),
         x -> maxpool(x, (2,2)),
         Conv((2,2), 16=>8, relu),
         x -> maxpool(x, (2,2)),
         x -> reshape(x, :, size(x, 4)),
         Dense(288, 10), softmax)
>>> FLuxJS.compile("mnist",m, rand(10))
Error: StackOverflow

The error message is too big.

[MikeInnes]

Yeah, we need a primitive definition that tells FluxJS how to map Julia convolutions to JS ones; something the the softmax one.