Email notifications (async microservice)

[alindgren]

Use RabbitMQ or Azure Queue Storage to queue a message send.

[alindgren]

A few thoughts:

• notifications should be logged
• create a good template system or way to plugin different providers (SendGrid, etc)
• could be done in a generic way as it's own project that could be used for other systems
• eventually may want to support other types of messages (SMS, FB messenger, Slack, Skype)
• eventually may want to lookup user notification preferences (via User microservice?)