Multiplication fix.

[amitjamadagni]

The following case fails

julia> a = full(tensor(lowerop(2), QuArray(eye(2))))
4x4 QuMatrix in FiniteBasis{Orthonormal}:
...coefficients: Array{Float64,2}
[0.0 0.0 1.0 0.0
 0.0 0.0 0.0 1.0
 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0]

julia> sm = full(tensor(QuArray(eye(2)), lowerop(2)))
4x4 QuMatrix in FiniteBasis{Orthonormal}:
...coefficients: Array{Float64,2}
[0.0 1.0 0.0 0.0
 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 1.0
 0.0 0.0 0.0 0.0]

julia> a*sm'
4x4 QuMatrix in FiniteBasis{Orthonormal}:
...coefficients: Array{Float64,2}
[0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0
 0.0 1.0 0.0 0.0
 0.0 0.0 0.0 0.0]

the last one has to be

julia> a*sm'
4x4 QuMatrix in FiniteBasis{Orthonormal}:
...coefficients: Array{Float64,2}
[0.0 0.0 0.0 0.0
 0.0 0.0 1.0 0.0
 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0]

[acroy]

Well spotted! Could you add a test for this case? (I guess something like sigmax*sigmaz' vs coeffs(sigmax)*coeffs(sigmaz)' would be sufficient)

[amitjamadagni]

@acroy tests added and squashed. Ready to be merged !

[amitjamadagni]

@acroy I hope this is ready.