Error thrown when calling `rand(d::GaussianLaguerre, dims::Dim2)` method

[apkille]

While writing docstrings for rand methods I found this:

julia> rand(GaussianLaguerre(2, 1.0), (3, 3))
ERROR: UndefVarError: `a` not defined in `RandomMatrices`
Suggestion: check for spelling errors or missing imports.
Stacktrace:
 [1] rand(d::GaussianLaguerre, dims::Tuple{Int64, Int64})
   @ RandomMatrices ~/Documents/Julia Packages/JuliaMatrices/RandomMatrices.jl/src/GaussianEnsembles.jl:180
 [2] top-level scope
   @ REPL[54]:1

Originates from not accessing a from the object d. Tests should be added for this method too as it looks a little suspicious as is:

RandomMatrices.jl/src/GaussianEnsembles.jl

Lines 149 to 173 in c76044d

	mutable struct GaussianLaguerre <: ContinuousMatrixDistribution
	beta::Real
	a::Real
	end
	const Wishart = GaussianLaguerre
	#Generates a NxN Hermitian Wishart matrix
	#TODO Check - the eigenvalue distribution looks funky
	#TODO The appropriate matrix size should be calculated from a and one matrix dimension
	function rand(d::GaussianLaguerre, dims::Dim2)
	n = 2.0*a/d.beta
	if d.beta == 1 #real
	A = randn(dims)
	elseif d.beta == 2 #complex
	A = randn(dims) + im*randn(dims)
	elseif d.beta == 4 #quaternion
	#Employs 2x2 matrix representation of quaternions
	X = randn(dims) + im*randn(dims)
	Y = randn(dims) + im*randn(dims)
	A = [X Y; -conj(Y) conj(X)]
	error("beta = $(d.beta) is not implemented")
	end
	return (A * A') / dims[1]
	end

[apkille]

Alongside of this, the β field should also be properly typed, as the current definition of GaussianLaguerre requires that it be real, which doesn't really make sense.