Remove extension from this feature-branch
Remove data-export functions
Move message classes to separate file.

Simplify conversion between messages and models.

Lint fixes.
Update README.md to hard break at 80char
Merge pull request #1 from christhompson/backend-submission

Backend survey submission
Merge remote-tracking branch 'upstream/master'

Conflicts:
	backend/models.py
	backend/survey_backend_api.py