1. Add support for `RAILS5=1|true` for the `bin/spinach` command.
2. Synchronize used spinach versions both for rails4 and rails5.

For rails5 it was accidently used spinach 0.10.1 instead of 0.8.10.
That brought some problems on running spinach tests.

Example of failure message:

NoMethodError: undefined method `line' for #<Spinach::Scenario:0x000000000c86ba80>
Did you mean?  lines
  /builds/gitlab-org/gitlab-ce/features/support/env.rb:52:in `before_scenario_run'

In Rails 5.0 `assert_template` and `assigns()` have been extracted to
the `rails-controller-testing` gem.
https://github.com/rails/rails/pull/20138/files

This commit adds this gem for rails5.

1. Synchronize used version of `parser` gem for both versions of rails: 4 and 5.
2. Fix broken CI pipelines for rails5 branches.

The 2.5.0.4 version is removed from rubygems, so it's skipped.
https://github.com/whitequark/parser/issues/478

- only older ruby and activerecord support dropped

These warnings would show when running rspec:

```
warning: parser/current is loading parser/ruby23, which recognizes
warning: 2.3.5-compliant syntax, but you are running 2.3.6.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.
```

Related PRs:

* https://github.com/whitequark/parser/pull/422
* https://github.com/mbj/unparser/pull/79

Related to gitaly#1060

Given 1.9 has issues we're aware of, for now we're locking to 1.8.
Closes gitlab-org/gitaly#1059 and will probably be removed if 1.10 is
tested an deemed ok.

Closes gitaly#1046

36847 - add changelog

26039 - add merge request id


26039 change due to lingust source file updates

Closes gitaly#985

Closes gitlab-org/omnibus-gitlab#3128

Gem is updated from 2.8 to 2.10. [changelog][1]

[1]: https://github.com/seattlerb/flay/blob/master/History.rdoc

Implements the client side for gitlab-org/gitaly#819. Which is a server
info command. This checks the server version and git binairy version on
the server.

A small UI was added for administrators, so they can check the status of
the Gitaly server. This is done for each storage the monolith knows.

Because of this commit, gitlab-org/gitlab-ce!15580 is now closed. That
MR removed the Git version too, but didn't replace it with anything.

Closes gitaly#979

Closes gitaly#967