Add e2e validation job for sidekiq-alive

[andrcuns]

It would be very useful to have additional validation layer that checks sidekiq-alive is working in a real app scenario.

This could be done based on packaging example app in to a docker container and seeing if it returns the proper health check status.

@arturictus Would You mind givin me maintainer access in https://github.com/arturictus/sidekiq_alive_example repo? I would like to give this a try when I have a moment.

[lucastosetto]

@andrcuns Do you still plan to work on this? If not, I'd be glad to help @arturictus .

[andrcuns]

@andrcuns Do you still plan to work on this? If not, I'd be glad to help @arturictus .

@lucastosetto Not at the moment, no.