Update Mission Vision and Values

[dfsnow]

The Mission, Vision, and Values section of the handbook hasn't been touched in awhile. We may want to revisit this section to make sure it aligns with where the Department is headed.

Some specific edits that should be made:

• Trim down the number of values. It's hard to embody values when you can't even remember them all. We should pare back to the ones that really matter and collapse similar ones. Something like the social rules of the Recurse Center might be more useful.