Handle missing environment from non empty config

If using a `DATABASE_URL` and a `database.yml`. The connection information in `DATABASE_URL` should be merged into whatever environment we are in. As released in 4.1.0rc1 if someone has a database.yml but is missing a key like production:

```yml
development:
  host: localhost

```

Then the check for blank config will return false so the information from the `DATABASE_URL` will not be used when attempting to connect to the `production` database and the connection will incorrectly fail.

This commit fixes this problem and adds a test for the behavior.

In addition the ability to specify a connection url in a `database.yml` like this:

```
production: postgres://localhost/foo
```

Was introduced in 4.1.0rc1 though should not be used, instead using a url sub key

```
production:
  url: postgres://localhost/foo
```

This url sub key was also introduced in 4.1.0rc1 though the `production: postgres://localhost/foo` was not removed. As a result we should not test this behavior.
Add tests for default scope behaviour change

See #13875
dynamically define PostgreSQL OID range types.

This gets AR working with custom defined range types. It also
removes the need for subtype specific branches in `OID::Range`.

This expands the interface of all `OID` types with the `infinity` method.
It's responsible to provide a value for positive and negative infinity.
deprecate support for pg ranges with excluding beginnings.

The Ruby Range object does not support excluding beginnings.
We currently support excluding beginnings for some subtypes using
manually by incrementing them (now using the `#succ` method).
This is approach is flawed as it's not equal to an excluding beginning.

This commit deprecates the current support for excluding beginnings.
It also raises an `ArgumentError` for subtypes that do not implement the `succ`
method.

This is a temporary solution to get rid of the broken state. We might still
add complete support for excluding beginnings afterwards. (Probably with a
new `PGRange` object, which acts like a `Range` but has excluding beginnings.
update version to 4.2.0.alpha
Merge pull request #13793 from senny/postgres/dynamic_range_oid

Dynamically define PostgreSQL Range OIDs
Coerce strings when reading attributes.
Introduce Concern#class_methods and Kernel#concern
Extract local cache middleware

Extract LocalCache Middleware, so it can requires rack dependencies,
without adding rack dependencies to `AS::Cache::Strategy::LocalCache`.
Group assets options in production env template
Merge pull request #14171 from arthurnn/extract_middleware_cache

Extract local cache middleware
Merge pull request #10497 from senny/10485_does_not_coerce_strings

coerce strings when reading attributes
include names in model generator warning message. refs #13515.

This is a follow up to #13515. It includes the name given and
the singularized version in the warning message. This will aide the user
to see wether the detected singular was right or not.
build fix. follow up to 174c9f0df39cd338a4871f82794256cc64f68a81
Simple Sungularize ActionController::UnpermittedParameters error in case when only 1 parameter is unpermitted.
refactor, extract `with_locale` helper.
Go with #presence_in instead of #present_in -- it doesnt sound quite as good, but the closer relationship to #presence over #present is ultimately worth it
Fix ActionView label translation for more than 10 nested elements
Merge pull request #14170 from kritik/master

there could be more than 10 nested records
refactor, with_locale is not needed because I18n is mocked.

This is a follow up to #14170. While backporting I recognized
that this call is not needed at all.