initial comment system

src/resources/activity/activityControllers.js

src/resources/activity/activityModel.js

src/resources/application/applicationRouter.js

src/resources/attendance/attendanceControllers.js

src/resources/attendance/attendanceModel.js

src/resources/comment/commentControllers.js

src/resources/comment/commentModel.js

src/resources/comment/commentRouter.js

src/resources/solution/solutionControllers.js

src/resources/solution/solutionModel.js

src/resources/task/taskControllers.js

src/resources/task/taskModel.js