Configure all webapps with Sentry.

• configure a project for the webapp in Sentry: https://wiki.umiacs.umd.edu/staff/index.php/Sentry#Configuring.2FAdding_a_New_Django_Project_in_Sentry
• add raven as a dependency
• remove django.utils.log.AdminEmailHandler if present
• add to INSTALLED_APPS
• add RAVEN_CONFIG to production-settings.py Pull in the DSN with summons to avoid committing secrets to the gitlab repo.