add statistics route with methods to show number of tickets and average wait time
change averageWaitTime to give whole numbers
add some basic styling for statistics page
refactor statistics controller to scope to closed tickets

Before the number of tickets counted all tickets, even open ones. For stat purposes, it made more sense
to count only closed tickets, since they represent something a teacher has done to help a student.
This made calucating average wait times much easier since we no longer needed to filter out tickets without
closedAt timestamps.
update README to reflect new user story priority
change background color to white on the statistics page
add tickets per hour graph to statistics page
allow average wait time to automatically switch from seconds to minutes if the count gets too high
adjust class for chart because break points were not working properly
update versions of files for ios caching