Rewrote the TensorBase::random method to support the generation of random number on gpu.

unsupported/Eigen/CXX11/src/Tensor/TensorBase.h

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorBase.h b/unsupported/Eigen/CXX11/src/Tensor/TensorBase.h
index 90a9cc2..d4b7846 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorBase.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorBase.h
@@ -39,9 +39,14 @@
     }
 
     EIGEN_DEVICE_FUNC
-    EIGEN_STRONG_INLINE const TensorCwiseNullaryOp<internal::scalar_random_op<Scalar>, const Derived>
+    EIGEN_STRONG_INLINE const TensorCwiseNullaryOp<internal::UniformRandomGenerator<Scalar>, const Derived>
     random() const {
-      return TensorCwiseNullaryOp<internal::scalar_random_op<Scalar>, const Derived>(derived());
+      return TensorCwiseNullaryOp<internal::UniformRandomGenerator<Scalar>, const Derived>(derived());
+    }
+    template <typename RandomGenerator> EIGEN_DEVICE_FUNC
+    EIGEN_STRONG_INLINE const TensorCwiseNullaryOp<RandomGenerator, const Derived>
+    random() const {
+      return TensorCwiseNullaryOp<RandomGenerator, const Derived>(derived());
     }
 
     // Coefficient-wise unary operators