Add default (and custom) timeout to --detach=false option

[WTFKr0]

Description

Is there a possibility to add a timeout to all --detach=false ?
In case the tasks are not shchedulable, the process seems to hang for ever
We use this in our CI to get status of the create/update service command
The workaround is to not use this option and check the status manually...

Steps to reproduce the issue:

1. docker service create --name testservice --detach=false --constraint node.platform.os==bados nginx:alpine

Describe the results you received:
Hang for ever

Describe the results you expected:
Hang for a time, and then display a message, like :

timeout reach
Operation continuing in background
Use `docker service ps id` to check progress.

[dnephin]

#665 adds a timeout. I think a default of false (no timeout) is still correct. I don't think there is any single value that can work as an acceptable default so we should keep the existing behaviour as the default.

[WTFKr0]

Agree for the existing behavior as default, and thanx