Created design documentation.

- Removed unused classes.
- Created component diagram. (Available at https://www.draw.io/?#G0ByyXLa89xHUdUHh2N1RyUE04RkE)
- Design documentation.
- Created architecture diagram. (Available at https://docs.google.com/drawings/d/1AVK6fYs7z_yCu2CLl-BDmpRw0_lMgh6SpE24JLdcwnw/edit?usp=sharing)
- Created deployment diagram. (Available at https://www.draw.io/?#G0ByyXLa89xHUdQTBrcDlXQjllcUU)
- Updated documentation.