Rubocop: Require space round operators

This is something I sometimes forget, and we shouldn't waste valuable Merge Request Endbosses time with that anymore: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/380/diffs#3b2db34301e25e02cccc0ff6ca78e7657733b640_72_74

So the ideia is to enable this cop:

# Use a single space around operators.
Style/SpaceAroundOperators:
  Enabled: true

And run an rubocop autofix to get everything in place.

Experimentally running with this cop enabled lead me to this result:

1688 files inspected, 102 offenses detected

This also catches unspaced uses of => like in : { 'Content-Type'=>'application/json' }

cc @rspeicher @DouweM

Sounds good to me.

@brodock Don't forget to check if EE has more offenses. We don't want to start getting failed master builds after merging.

mentioned in merge request !4112 (merged)

Reassigned to @rspeicher

Reassigned to @brodock

Status changed to closed by commit 5e130c3e

mentioned in commit 5e130c3e