workshops/migrations/0026_auto_20141210_1537.py: Add event.notes and site.notes

This should have happened before the notes content was merged in
3861aeed (Merge pull request #60 from pbanaszkiewicz/notes,
2014-12-15).

This is the template created with:

  $ python3.4 ./manage.py makemigrations
db.sql: Migrate to event.notes and site.notes

With:

  $ make database
  $ python3.4 ./manage.py migrate
  $ sqlite3 db.sqlite3 .dump > db.sql

This should have happened before the notes content was merged in
3861aeed (Merge pull request #60 from pbanaszkiewicz/notes,
2014-12-15).
Merge pull request #92 from wking/notes-migrations

Add a migration for event.notes and site.notes