Configurable docker networks

[iamkubi]

Add the ability to create docker networks and assign servers to them. Currently all servers are created on a single docker network which can cause security issues for things like Minecraft networks.

• UI in the Node admin for managing Docker networks
• Wings APIs for managing networks
• Panel APIs for managing networks

By default Docker can only create 29 networks which seems a little low to me. This can be adjusted by providing additional internal IP subnets to the Docker config, but we can just document that under advanced configuration.

Due to this limit on networks I don't think network creation should be exposed to end users. Admins will need to create networks and add servers to networks and advanced users will be able to do this with the API.

As a future improvement we might allow users to create and manage their own networks with limits, similar to how user assigned additional allocations work.