Add the "lazy start" technique to initialization stage

Previously, if an instance was started in read_only mode, it could throw an error when initializing the queue module, like this: "Can't modify data because this instance is in read-only mode". To avoid such behavior the "lazy start" technique has been added: The queue module is loaded immediately if the instance was configured with read_only = false. Otherwise, a start is delayed until the instance will be configured with read_only = false.

Closes #122

ChangeLog: add the ability to start an instance with a loaded queue module in read-only mode. In this case, a start of the module will be delayed until the instance will be configured with read_only = false.

tarantool / queue

Add the "lazy start" technique to initialization stage #131