Update img/assign.jpg, img/assigned.jpg, img/newproject.jpg, img/signin.jpg, img/student_board.jpg, img/upload.jpg, img/list_student.jpg, img/newassignment.jpg, img/newcourse.jpg, img/newstudent.jpg, img/open_assignment.jpg, img/tp_prof_board.jpg, img/tp_prof_chat.jpg, img/upload2.jpg, img/tp_student_crossview.jpg, img/tp_prof_crossview.jpg, img/tp_student_open.jpg, README.md files
Deleted images/.gitkeep, images/assign.jpg, images/assigned.jpg files