Related to 2e0fe592

It was brought to my attention that the Rails guide suggests using filenames to ensure code load order, so I thought I would suggest a better alternative.

Compression has long been available, but opt-in and at a 16kB threshold.
It wasn't enabled by default due to CPU cost. Today it's cheap and
typical cache data is eminently compressible, such as HTML or JSON
fragments.

Compression dramatically reduces Memcached/Redis mem usage, which means
the same cache servers can store more data, which means higher hit
rates.

To disable compression, pass `compress: false` to the initializer.

* Supports vanilla Redis, hiredis, and Redis::Distributed.
* Supports Memcached-like sharding across Redises with Redis::Distributed.
* Fault tolerant. If the Redis server is unavailable, no exceptions are
  raised. Cache fetches are treated as misses and writes are dropped.
* Local cache. Hot in-memory primary cache within block/middleware scope.
* `read_/write_multi` support for Redis mget/mset. Use Redis::Distributed
  4.0.1+ for distributed mget support.
* `delete_matched` support for Redis KEYS globs.

Passing the environment's name as a regular argument is deprecated
in 48b24992.

We have already specified to install `bundler` 1.15.4 in `.travis.yml`.
https://github.com/rails/rails/blob/master/.travis.yml#L31..L32

However, `bundler` 1.16.0 may be used in the test.
https://travis-ci.org/rails/rails/jobs/296582467#L2208

The test failed due to this influence.
In order to avoid this, specifying `bundler` version in bug report
templates.

Follow up of #31004.

This is useful to extend `SystemTestCase`.
Also, since other test classes already have load hooks, should also be
in `SystemTestCase`.

Ref: 0510208d

Evented Redis adapter was removed in 48766e32.

The documentation wrongly suggests that Time extensions to Numeric include
methods months and years, when these belong to Integer.

Update both classes and guides.

Evented Redis is removed from Rails.
See #30945

The example was slightly incorrect. This commit also adds a test case
for this example to cookies middleware unit tests.

The default of `String#to_time` is `:local` since b79adc43.

Resemble links to Bundler and Yarn,
based on feedback by @kamipo

[ci skip]

The link to recaptcha.net returns a 404. As far as I can tell, the new
link ought to be to https://developers.google.com/recaptcha/ .