Allow failures until test runs are consistently stable, not hanging.

Closes #24943.
Signed-off-by: NJeremy Daer <jeremydaer@gmail.com>

Apps that depend on Action Cable don't need Blade for app development,
so we can remove the gem dependency.

We do need Blade for Action Cable dev, so we bundle it in the Gemfile.
Signed-off-by: NJeremy Daer <jeremydaer@gmail.com>

- Followup of https://github.com/rails/rails/pull/24946.

Resolved by https://github.com/ruby-concurrency/concurrent-ruby/pull/529

Fixes #24627.

Without the `wdm` gem, it appears that `listen` keeps an open handle to
each of these files, causing them not to be removed when the tempdir
tries to clean iteslf up, and then directory to fail to unlink. In
addition to fixing that particular failure, we now construct OS agnostic
paths, and capture exceptions if the directory fails to unlink so that
minitest will report it rather than crash

'rake' gem is bundled to '>= 11.1' by 30279704
(#23499), but it seems the commit did not fully include Gemfile.lock's.

Uses latest precompiled JRuby so that
we don't spend time downloading versions Travis has
not already compiled. http://rubies.travis-ci.org/

Uses latest jdk: oraclejdk8
per
https://docs.travis-ci.com/user/build-environment-updates/2015-02-03/#Ruby-VM
and
https://docs.travis-ci.com/user/languages/ruby/#Supported-Ruby-Versions-and-RVM

Follows on work in https://github.com/rails/rails/pull/23927 which was reverted
https://github.com/rails/rails/commit/26fe5fa08d52384bcea09c4210e3b3baaf5e9b95

JRUBY_OPTS minimize GC, disable JIT, for max test speed
  - https://github.com/rails/rails/pull/16613
  - https://github.com/rails/rails/pull/17088

Have Rails use JRuby-compatible Rake 11.1
  - The Rake task was passing --verbose, an invalid option, to contemporary JRuby
  - https://github.com/ruby/rake/pull/120
  - https://github.com/rails-api/active_model_serializers/pull/1585
  - https://github.com/jruby/jruby/issues/3653#issuecomment-195883717

No advantage to directly mounting JRuby over installing from cache; both on S3
  - https://github.com/rails/rails/pull/23499/commits/b2d5b336b5a812009444571b22eed90777cd9a8c
  - https://github.com/rails/rails/pull/23499/commits/f4fad041b2755d81e82ee3fc66d96f334b4653db

- Resque version was locked to < 1.26 in 92f869a0 but
  Gemfile.lock was not updated.

dalli 2.7.6 fixed deprecation warning caused by using
`Rack::Session::Abstract::ID`.
This commit suppress warnings on ActionPack tests.

See:
https://github.com/petergoldstein/dalli/commit/9874a7c3ad67eb1e31cafba0a51966db4f0c7e42

Ref - https://github.com/turbolinks/turbolinks-rails/pull/3

railties uses method_source, activesupport does not.  I assume code was refactored and the dependency wasn't removed.

All modern Rubies ship JSON as part of stdlib.  Using the gem actually hurts multi-platform support due to build difficulties on Windows.

- Leftover from https://github.com/rails/rails/commit/93abf58787396661230f31c7a2f58c18f30dbec9.

This new adapter does get a little more intimate with the redis-rb gem's
implementation than I would like, but it's the least bad of the
approaches I've come up with.

This PR includes two changes for 2.0.0:

- Breaking API change around `async.perform` --> `perform_async`
- New addition of `perform_in`, which now allows end users of the
  adapter to use the `enqueued_at` public API method.

(as adapted to use concurrent-ruby / nio4r instead of eventmachine)

- adapter -> pubsub (re)rename internally
- Change variable names to match method names
- Add EventMachine `~> 1.0` as a runtime dependency of ActionCable
- Refactor dependency loading for adapters

- Eventmachine version gets updated when `bundle` is run locally.