Ex-74 Registration Code redemption

fix the translation issues

added a check if a user is already registered in a course. Changed the messages

added course depth=0 and removed pep8 violations

Ex-72-added additional billing information

Added a new CSV file in the instructor dashboard sales tab to download all the order sales separated from the invoice sales

fix path to image

updated the failed unit tests and add some minor tweaks in the Shoppingcart.scss

Ex-78 New UI In receipt page

EX-73 Purchasers can buy a course on behalf of a different student

WL-78 updated the receipt page UI.

Wl-72 updated Billing Information UI and removed the Order Address fields

WL-71 Remove Purchase Type Buttons from UI

WL-71 Updated minor UI issues and updated test cases

WL-78 updated the enrollment links in the receipt page

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

WL-97 Bulk Registration Email Confirmation
Below is the commit summary.
- Make email text bold as per requirement.
- Improve email template quality and reorder points.
- Add text in billing details page : "if no additional billing details are populated the payment confirmation will be sent to the user making the purchase"
- Update text on receipt page "You have successfully purchase 3 course registration codes"

WL-100 fixed the bug on the edit/add coupon and set course price.
Ajax requests were duplicating in each callback. fixed this issue by creating the manual ajax request rather than the Lean Modal Ajax requests

allow for better White Label branding in shopping cart purchase emails

fix up typos and text

fix goof

fix

fix

incorporated model changes as suggested by Jason.

updated order sales csv

updated test cases for CourseRegCodeItem model and csv for the order generated sales

updated the migrations history

fixed the lms acceptance tests

Be sure to check for multiple types

address PR feedback

PR feedback

PR feedback

pep8 fix