[BOT] Display multiple grades

[derekantrican]

Instead of just using the current grade, we should show multiple grades. Like:

Grade: 5.9- | 5c | VI

(or something like that)

Some other thoughts:

• Should we remove the "Grade Conversion" link at the bottom?
• We shouldn't display the grade system name
• If someone uses the -grade operator maybe we should list that one first in the list
• Should maybe think about the best "separator" to join the grades together