Squashing commits

Transition to Oqaque Keys

Bug fixes

Fixing regenerate_user

[LMS-2757]

sorted the output, easier to read

Add is_active filter to only generate for students enrolled

Adding back total_enrollment

Removing active filter

Certs will generate for all users in the course, not just those "active"

Typo

Renaming headings to make more sense

Renaming variables to match headings

This commit adds the non-courseware lms/djangoapps and lms/lib.

These keys are now objects with a limited interface, and the particular
internal representation is managed by the data storage layer (the
modulestore).

For the LMS, there should be no outward-facing changes to the system.
The keys are, for now, a change to internal representation only. For
Studio, the new serialized form of the keys is used in urls, to allow
for further migration in the future.

Co-Author: Andy Armstrong <andya@edx.org>
Co-Author: Christina Roberts <christina@edx.org>
Co-Author: David Baumgold <db@edx.org>
Co-Author: Diana Huang <dkh@edx.org>
Co-Author: Don Mitchell <dmitchell@edx.org>
Co-Author: Julia Hansbrough <julia@edx.org>
Co-Author: Nimisha Asthagiri <nasthagiri@edx.org>
Co-Author: Sarina Canelake <sarina@edx.org>

[LMS-2370]

Also removes the unnecessary pre-fetch.
For certificate generations we will continue to generate certs for
both active and inactive users.

For the report we only display active users since it was confusing
due to the instructor dashboard only displaying active users.

* -G allows explicit setting of grade condition (e.g., a string such as
  'Distinction', 'Pass', 'F', 'B') for the certificate, regardless of
  grader output for the user.
* -T allows explicit request of a particular certificate template to be
  applied to a given user's certificate regeneration, i.e.:
    -T doctor_distinction.pdf
  to generate a certificate of distinction for doctors.

* output after cert_whitelist -a or -d purported to be the whitelist entries
  for the requested course, but in fact were all of the entries in every
  course. This commit fixes that.

* Adds regenerate_user command, which lets you run certificates for one
  particular user in one particular class, regardless of whether they
  have a pre-existing certificate.

It doesn't make sense to print out unavailable students
since it will go negative as students unenroll

This will allow you to force the certificate generation
for when certificate requests are lost and stuck in
'generating', this happens when we have xqueue issues.

graded

* List of courses that have ended is now a generator
* Using db-aggregation to speed up query for tallies

* Removing the command to find unicode names since it was only used for
  testing
* ungenerated_certs will now by default run through all courses that
  have ended.  a course option can be used to run on one course
* gen_cert_report added which will summarize certificate states
  for all courses that have ended

enrolled_students query