Create a post-lab statistics page

Required statistics:

• average waiting time per hour
• requests over assignments
• requests over rooms
• number of waiting students
• graph over entire lab
  • average waiting time per hour
  • average processing time
  • active assistants
  • active students
• bar graph for request statuses
• TA velocity: have a threshold for handling requests to determine abundance/lack of TAs per lab
• Detailed TA statistics page
  • TA name
  • Timestamp of first accepted request in the lab
  • Timestamp of la(te)st accepted request in the lab
  • Total number of requests handled in this lab
  • Average time spent per request in this lab
  • see #240 (closed) for more detail