Add a database store driver

Add a database-backed store to be a complementary choice to the initial NodeRAMStore.

[Kaliph]

It would be great if you would add Sequelize

Sequelize

[Kaliph]

One question I have regarding a database store driver. Is there already an object that represents the nodes and their devices, flows, receiver, senders? Or do I have to collect the data from the Registration API. I would like to know where is the best place in code to add a Database driver. Thankyou