ruby 2.1. failing very frequently in master

As mentioned by @vsizov, the Ruby 2.1 builds are failing in master very frequently as they are not split into smaller builds:

Actually I don't think this is a good idea to add these builds because we have lots of sporadic failings and adding whole test suite run makes that builds long

This should be a straight forward change just to split the spec and spinach builds into the same as with Ruby 2.2.

Feel free to comment on this in case there are any objections...

/cc @dzaporozhets @DouweM

mentioned in merge request !2746 (merged)

Maybe we can use one official ruby version instead of ruby zoo?

@vsizov If we want to continue to support 2.1, we need to run tests against that too. (https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2534#note_3391417)

Status changed to closed by merge request !2746 (merged)

mentioned in commit 2837f5c1

Mentioned in commit pfjason/gitlab-ce@2837f5c1