Update TEACHERS.md
Moving folder around first
Refactor first exercise of migration
spelling
Move file around first
Second exercise on model refactored
Move seed from day 4 to day 3
README updated for 2 seed exercises
Forgot json
s/100/10
Merge branch 'master' of github.com:lewagon/promo-4-challenges
Remove old exercise
Basic one-to-many association
Remove MVC for this first exercise
Remove old validation exercise
Validation exercise
Fix URL
Fix spec
Regex validation
Add some reference to callbacks