Flint: Rework startup
As i have a better understanding of gevent/rpc... there is improvement which can be done for the Flint start up.
This also will helper to retrieve information when Flint is stucked. Such hotfix is already deployed at ID15A in a dirty way.
This could handle #2565 (closed) #2265 (closed) and merge together !3443 (merged) !3437 (merged)