Add tests for randn! and randexp! (#189)

Author: kshyatt

test/MArray.jl

@@ -57,6 +57,9 @@
         @test isa(@MArray(rand(2,2,1)), MArray{Tuple{2,2,1}, Float64})
         @test isa(@MArray(randn(2,2,1)), MArray{Tuple{2,2,1}, Float64})
         @test isa(@MArray(randexp(2,2,1)), MArray{Tuple{2,2,1}, Float64})
+        
+        @test isa(randn!(@MArray zeros(2,2,1)), MArray{Tuple{2,2,1}, Float64})
+        @test isa(randexp!(@MArray zeros(2,2,1)), MArray{Tuple{2,2,1}, Float64})
 
         @test ((@MArray zeros(Float32, 2, 2, 1))::MArray{Tuple{2,2,1},Float32}).data === (0.0f0, 0.0f0, 0.0f0, 0.0f0)
         @test ((@MArray ones(Float32, 2, 2, 1))::MArray{Tuple{2,2,1},Float32}).data === (1.0f0, 1.0f0, 1.0f0, 1.0f0)