defined sessions_list method in boss controller
added has many association in period model
added all sessions link
created route for list sessions
view for listing all sessions
route for all submissions for a session
added arrange abstracts link
added ranked model gem
defined submissions for periods controller with initial view for it
added row_order column to allotments
included ranked model in allotment
get allotments in ranked order in submissions method of periods controller
added arrange method for allotments
sortable functionality for abstract submissions
route for arrange method of allotment