Save transcript credentials backend view

logging and cleanup

Add JWT settings

Divide settings into environment specific sub modules

refactor config setting file read

changes for config role

Transcripts 3rd party integration

3Play Media translation process improvements

EDUCATOR-1468: Includes the following:
- Translation retrieval process do not use the ranslation endpoint which was previously changed by 3PlayMedia
- Make a single call to retrieve all the translation metadata for a video
- Add 100% test coverage for the modified patch

- Fix - HEAL overwrite transcript statuses for completed videos in VAL.
- Add source_language and transcript_status to VideoSerializer and Admin.
- Add tests coverage for Model Serializers.

EDUCATOR-1431 - HEAL process was overwriting transcript statuses as they were combined with transcode statuses. So, separated them out to avoid unnecassary masking of Video's transcript statuses.

token should not use - OR any other character as per regex in url.

File "/home/ec2-user/edx-video-pipeline/VEDA/django_secrets.py", line 24, in <module>
:     DJANGO_DEBUG = return_dict['debug']
: KeyError: 'debug'

- improve logging
- VEDA vedio status updation
- Remove celery task for retriving 3Play translations, accomodate it in heal process
- improve __unicode__ method and add help text
- Add an ability to override developer configs

This implements 3PlayMedia API integration in pipeline.
Other than that it also iuncludes:
-- rename 'Transcript Preferences' to 'Transcript Credentials'.
-- Add migrations.
-- Rename 'Transcription Ready' to 'Transcript Ready'.