When I set this problem:

```
data = [2;3;4;-1;0]
model = Model(with_optimizer(GLPK.Optimizer))
@variable(model, x[1:length(data)], Bin)
@objective(model, Min, sum(data.*x))
optimize!(model)
typeof(value.(x))
```

I would expect the type of `x`

to be `Array{Bool,1}`

but I get `Array{Float64,1}`

instead. Is there a reason behind using Floats instead of Bools for binary constraints?