address review comments

src/ngraph/descriptor/input.hpp

@@ -46,6 +46,7 @@ namespace ngraph
             size_t                get_arg_index() const { return m_arg_index; }
             size_t                get_index() const { return m_index; }
             const Output&         get_output() const { return m_output; }
+            Output&               get_output() { return m_output; }
 
         protected:
             Node*   m_node;      // The node we are an input for

src/ngraph/descriptor/output.hpp

@@ -26,6 +26,8 @@ namespace ngraph
         // Describes an output tensor of an op
         class Output
         {
+            // For some odd reason emplace_back is requiring a copy constructor
+            // it should not. See issue #111 for details
             // Output(const Output&) = delete;
             // Output& operator=(const Output&) = delete;