Support for Unitful quantities?

[lmiq]

Is this expected to work? (related to https://github.com/PainterQubits/Unitful.jl/issues/46):

julia> using LinearSolve, Unitful

julia> A = rand(3,3)u"nm"; x = rand(3)u"nm";

julia> solve(init(LinearProblem(A, x)))
ERROR: DimensionError: nm and false are not dimensionally compatible.
Stacktrace:
...

[ChrisRackauckas]

It doesn't work right now. We'd have to specialize it or Unitful would have to fix the more fundamental issue here.