Allow overriding migration servers

[aliismayilov]

This would enable users to run migrations on multiple servers. I've seen this being discussed at capistrano/capistrano#1449.

Unlike #127, it doesn't change the existing functionality. And unlike #126 it actually works.

In our case, we would be able to override the migration_servers value with set :migration_servers, -> { release_roles(fetch(:migration_role)) }

[mattbrictson]

Excellent work! ✨
Can you add a mention of this new feature under the "master" heading of the CHANGELOG?

[aliismayilov]

Thanks for a quick feedback! I've amended CHANGELOG changes.

[mattbrictson]

Thanks for the PR! 🙇

[Bertg]

Can we have a 1.1.7 release for this please? Would be very appreciated :)

[mattbrictson]

I would be happy to, but I don't have gem publishing rights. For that you will need to get the attention of @kirs.

[Bertg]

@kirs Can we have a 1.1.7 release for this please? Would be very appreciated :)

[kirs]

Pushed 1.1.7. Thank you for the PR!

I tried adding @mattbrictson as an owner but his email on Github is hidden and all it provides is mattbrictson@users.noreply.github.com.

[gregblass]

This just worked like a charm. Thanks to all involved!