Add new interface code

- Separate /users/:id/my_projects and /users/:id/my_submissions into
  four pages: two containing all projects or submissions for that user
  (at /users/:id/my_...), and two containing projects or submissions
  for that user from a given quarter (/:year/:season/my_...)

- Begin adding code to dynamically choose which quarters to show in the
  header

- Also, update gems