I guess it doesn’t make all that much difference which sign: it’s an arbitrary choice. It’s just a bit confusing for students to define the electron charge as -e instead of +e, or draw diagrams with arrows pointing the opposite direction of electron movement. http://www.allaboutcircuits.com/textbook/direct-current/chpt...
On the other hand this guy seems to appreciate the definition: http://www.austincc.edu/wkibbe/truth.htm