This removes the requirement and any mention of targeting security
branches when working on security releases. The release process
documentation changes for these CE changes can be found in merge request
https://gitlab.com/gitlab-org/release/docs/merge_requests/97.

The proposal to remove security branches was approved in
https://gitlab.com/gitlab-org/release/framework/issues/165#note_138139016.

Improve existing issue templates for security releases

Signed-off-by: Rémy Coutable <remy@rymai.me>

This adds additional options that make it easier to use this script:

1. It adds `--dry-run` option that only displays Git commands that are
going to be executed.
2. It adds `--remote` option that makes it possible to override Git
remote name.

* updates Gemfile
* uses Rails 5 unless explicitly disabled

This allows us (and others) to test drive Puma without it affecting all
users. Puma can be enabled by setting the environment variable
"EXPERIMENTAL_PUMA" to a non empty value.

Was introduced in the time that GitLab still used NFS, which is not
required anymore in most cases. By removing this, the API it calls will
return empty responses. This interface has to be removed in the next
major release, expected to be 12.0.

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'

Signed-off-by: Rémy Coutable <remy@rymai.me>

Moving the check out of the general requests, makes sure we don't have
any slowdown in the regular requests.

To keep the process performing this checks small, the check is still
performed inside a unicorn. But that is called from a process running
on the same server.

Because the checks are now done outside normal request, we can have a
simpler failure strategy:

The check is now performed in the background every
`circuitbreaker_check_interval`. Failures are logged in redis. The
failures are reset when the check succeeds. Per check we will try
`circuitbreaker_access_retries` times within
`circuitbreaker_storage_timeout` seconds.

When the number of failures exceeds
`circuitbreaker_failure_count_threshold`, we will block access to the
storage.

After `failure_reset_time` of no checks, we will clear the stored
failures. This could happen when the process that performs the checks
is not running.

Resolves gitlab-org/gitlab-ce#36417

Signed-off-by: Rémy Coutable <remy@rymai.me>

Added the type attribute to a CHANGELOG entry. When you create a new
entry the software asks for the category of the change and sets the
associated type in the file.