initial implemenation for email support
Merge branch 'master' into feature/email
model classes for email templates
continuing on the email notifications
support moving to completed
tweaks

- fixed a bug when moving to reflect stage
- added link to the actual challenge so that mentor can go to it
- added email for when the mentor has moved the progress to reflect stage
Merge branch 'feature/email' of https://github.com/camilaachutti/curiosityMachine