Add a persistent queue to hold events generated by SolarNetwork, so that hooks can be configured to execute when the events are received. Desired features of the queue:

1. Publish/subscribe model with topics
2. Shared subscription model, so only one subscriber gets any particular event at a time, allowing subscriber processors to scale with demand
3. JSON or similar message body support (e.g. CBOR)
4. Support re-try up to a configurable times in case a remote service fails to be called

The implementation of the queue should be considered in terms of:

• meeting feature requirements
• reliability
• scalability
• cost to deploy (i.e. cost to run associated queue infrastructure)