Adding checks to the alerts for student training.
Using the XBlock i18n Service for ORA2
Merge pull request #563 from edx/sanchez/fix-extra-training-alerts

Adding checks to the alerts for student training.
Merge pull request #564 from edx/sanchez/use-i18n-xblock-service

Using the XBlock i18n Service for ORA2
Update messages in authoring UI
Remove unsupported assessment configurations
Set default dates to something reasonable.