Appliation record documentation fixes

Merge Action Cable into master

[ci skip]

This is a pass over the documentation which fills the missing gaps of
`ApplicationRecord`.

[ci skip]

Since we require you to enable it on the client-side, let us do the
same on the server-side. Then you’re not running an EventMachine unless
you need to.

[ci skip] Fix grammar and sentence framing

Test against Ruby 2.2.4 on Travis.

fix typo in method name [ci skip]

It was changed by mistake at 428d47ad

This reverts commit 4d06ea9a, reversing
changes made to e9d15072.

Reason: This will break oracle-enhanced, see
https://github.com/rsim/oracle-enhanced/blob/3c42131db82b64ac41645db3affc6e4650289df6/lib/active_record/connection_adapters/oracle_enhanced_adapter.rb#L1254

`join_to_delete` is same as `join_to_update`

Add Logger option to disable message broadcasts

All public methods are tasks, so we need to move it to protected
visibility.

This test was failing when run on Windows using PostgreSQL. Depending on
the OS (and 32 vs 64 bit), this type could be a `BigNum`. We could loosen
the assertion to `Numeric`, but if the value is equal to the expected, and
responds to `bitlength` properly, who cares?

Rack::Server already does it work for us if the server is installed.

When setting the Rails logger to log to STDOUT, it would broadcast the
log twice in development. This adds a setting that will prevent messages
from being broadcast to multiple logs, while still allowing calls to
`#close`, `#level=`, `#progname=`, and `#formatter=` to be broadcasted.

Fixes #14769, #11415

I didn't mean to commit that!

Unlike unix, the TZ variable on Windows does not look at a database. It is
always expected to be in the form {Standard Time
Abbreviation}{UTC-Offset}{Daylight Time Abbriviation}. This changes the
relevant tests to use the Windows form when run from Windows.

Still missing the stuff in app/ – we need to basically switch from a *
match to specifically picking out what we need.