fix syntax error on 2.1 and rubocop on 2.2

Background:

Hashes {:'key': 'value'} are not valid in 2.1 but are recommended by Rubocop on 2.2. We only use those when we have a key such as weird-key, weird.key, etc...

We could disable Rubocop but it wouldn't warn us about the recommended syntax since Ruby 1.9: {key: 'value'}, which is valid for Ruby 1.9+.

Workaround 1 could be disabling Style/HashSyntax: in rubocop.yml.

Workaround 2 (tried in this MR) is to trick Rubocop using .to_sym which is effectively the same as adding the :. This would allow to keep the warning in place.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/12801

Added 44 commits:

• 902baa2e...88e16c3d - 43 commits from branch gitlab-org:master
• 69c4e0a1 - Merge branch 'master' of gitlab.com:gitlab-org/gitlab-ce into hotfix/ruby-21-broken-update

• update - Still waiting for the builds to run successfully - I am including ruby 2.1 temporarily so they are quite slow...

Added 1 commit:

• 6e4d36b4 - add back master only for ruby 2.1 images

Builds succeeded for both Ruby 2.1 and Ruby 2.2 - https://gitlab.com/jameslopez/gitlab-ce/commit/69c4e0a1197b21bf0b4925edcda0943be9e0e641/builds

Title changed from WIP: fix syntax error on 2.1 and rubocop on 2.2 to fix syntax error on 2.1 and rubocop on 2.2

Reassigned to @dzaporozhets

@dzaporozhets this is ready now - builds seem fine for both Ruby 2.1 and 2.2

/cc @DouweM in case you want to check this as well

mentioned in commit 9d0065f0

Status changed to merged

Sorry @dzaporozhets for jumping the queue and merging.

@marin you are welcome!