Implement Teacher Satisfaction survey in school profile

[jtf621]

@jtf621 has some data gathering scripts underway

[alexlemann]

Todo:

• [x] Add a new field to the School model (allow it to be null)
• [x] Create migration for the field
• [ ] Manually add schools from here: https://ncteachingconditions.org/results
• [ ] Fix the templates (take into account when it is blank)

[vinvasir]

@victor-rocha @alexlemann

I just started a new branch. So far I've just added the teacher_satisfaction_survey field as a URLField that can be null. Will make a new commit for the migration.

[vrocha]

+1

[vinvasir]

The branch is called "pv-school-survey-field"

[vinvasir]

Ran the migrations and didn't get any complaints from the Django console or Travis CI! Pull request located here.

Also happy to help with the data entry and template-fixing parts of the issue.