Fix #866: Route not found

If we mount a Grape::API app which using version and namespaces to another
Grape::API app, the version setting will lost.

lib/grape/endpoint.rb

@@ -99,7 +99,6 @@ def reset_routes!
     def mount_in(route_set)
       if endpoints
         endpoints.each do |e|
-          e.inheritable_setting.inherit_from inheritable_setting
           e.mount_in(route_set)
         end
       else

spec/grape/api_spec.rb

@@ -2415,6 +2415,21 @@ def static
         options '/v1/apples/colour'
         expect(last_response.status).to eql 204
       end
+
+      it 'mounts a versioned API with nested resources' do
+        class User < Grape::API
+          version 'v1'
+          resources :users do
+            get :hello do
+              'hello users'
+            end
+          end
+        end
+        subject.mount User
+
+        get '/v1/users/hello'
+        expect(last_response.body).to eq('hello users')
+      end
     end
   end