Encrypt the session id before writing to tracking logs.
Also use md5 for constructing key for hmac.
Update ddt to 0.8.0
Fixes BLD-1104
Add additional tests for tracking of sessions.
Merge pull request #3962 from edx/dcs/BLD-1104

Fixes BLD-1104
Text Annotation Tool: Added Instructor Filter and Clear Search
Video Annotation Tool: Added Instructor Filter
Image Annotation Tool: Added Instructor Filter
Image Annotation Tool: Annotation Mode for AB Testing

Annotation Tools PR Fixes

- forgot to overwrite the previous line
Annotation Tools: PR Fixes

- Fixed camel case for variable name
- Fixed indentation in imageannotation.html
- Changed all mentions of Instructor Username to Email
- Turned annotation_mode into phrase
- Fixed indentation in imageannotation.html
- Added comments in imageannotation.html

- Changing annotation_mode in OSDA
Annotator Tools: OpaqueKeys update for Notes
Annotation Tools: Added CommonAnnotatorMixin
Bugfix certificates request queue HTML flattening
Annotator Tool: Fixed delete bug and factored out settings

Removed print context
Merge pull request #2 from lduarte1991/lduarte-harvardx-pr3

Annotation Tools: Fix delete bug and factor out xmodule settings
Product stack documentation

DOC-448
fix nfsd in devstack
Merge pull request #3960 from edx/db/update-ddt

Update ddt to 0.8.0
Remove duplicates in a class list so tests aren't duplicated