Bundle cache on AWS S3

[shatrov]

I proposed to use a snippet to put bundle cache on AWS S3.
Benefits we get:

• bundle speedup on every build

• avoiding commited gems to the repo (ruby-bench-docker/ruby/ruby_releases/discourse_benchmarks/cache at master · ruby-bench/ruby-bench-docker · GitHub)

Sam, what do you think?

[sam]

Why S3 ? We can store the cache on the bare metal machine if needed outside the docker container, no reason to go all the way to S3 here

(btw upped your trust level so you can invite - also if you @mention us we get an email about the topic)

[shatrov]

Thanks!

I copied the implementation from the Travis CI and they use S3.
But actually, using the bare metal machine file system is even better.