Update Nav styling and Nav Buttons for XP show page

also updated db migrate file from "null" to "nill"
Update navigation link, update student index search, fix offerings csv import

Fixed import action in offerings controller and offering model.
Added course id as column to course index table.
Changed link in admin tasks so user views courses path instead of
Courses new page.
Added nav links to student edit page.
Removed students birth date and start date from student index table.
Added student offering so user can search by location day and time.
Additionally added parent email for future use of csv export for mass
emails.
Merge branch 'nav_update'

multiple updates