Evaluate zero-downtime updates

[andygrunwald]

For this, all sockets and file handles need to be passed to a new process that is started by the active Gollum process (no fork!).

The main challenge will be to correctly reassign the handles to the corresponding plugins in the new Gollum instance.

Config changes are not allowed when doing this.

Maybe we can use GOB + unix domain sockets to transfer data between both processes.

Important: This is just an idea and this ticket can be used for a discussion. You have ideas? Feel free to add them here. You have concerns? Add a comment! Or maybe you have an idea how to develop it? Feel free to run a prototype.

For this feature, the architecture change that is coming in v0.5 is required.