made changes in Order generated sales csv in Instructor Dashboard.
 The total_registration_codes and total_used_codes
  were not correctly stored in the csv file.

1) The total_registration_codes were not filtered with
 course_id.
2) The total_used_codes that a user had redeemed
 were not correctly included in the CSV.

added a fix in the courseware view to let the users visit the courseware if they have enrolled in the course by clicking on the enrollment link

rebase and resolved conflicts with master