Ensure that the Grade field data stays in clean_data. This prevents a bug that happens when you pick an invalid entry in the choice a grade field. If this bug was triggered the value of the survey_record.grade was used. Now however a proper ValidationError is raised.

# use glob syntax.
syntax: glob

*.pyc
*.zip
*~
.project
.pydevproject
app.yaml
build
tests/coverageResults
*,cover
tests/.coverage
*.git
.gitignore
.DS_Store
.settings