High availibility support

**Is your feature request related to a problem? Please describe.**
I want to run Gorse in a high availability setup. Now it is not possible to have multiple master nodes. If the master node is done, there is no backup.

**Describe the solution you'd like**
I want Gorse to support master-master replication. Multiple masters should be able to communicate with each other to orchestrate tasks.

**Describe alternatives you've considered**
There is an option to have duplicate Gorse with an identical configuration that is used as a backup if the first one is down. But these 2 Gorses would calculate recommendations redundantly because they know nothing about each other.

**Additional context**
We can discuss implementation details if needed.