Documentation and cleanup of automatic discovery of inverse associations

fixed typo in action_view template

Testing CheckPending middleware

of using +inverse_of: false+ option. Changing the documentation and
adding a CHANGELOG entry for the automatic inverse detection feature.

Time.at allows passing a single Time argument which is then converted
to an integer. The conversion code since 1.9.3r429 explicitly checks
for an instance of Time so we need to override it to allow DateTime
and ActiveSupport::TimeWithZone values.

Update Getting Started Guide - Strong Parameter [ci skip]

	modified:   guides/source/getting_started.md

This reverts commit 257fa689, reversing
changes made to 94725b81.

The build failed

https://travis-ci.org/rails/rails/builds/7883546

Improve performance of ActiveRecord::Relation#blank?

This is an SQL improvement to ActiveRecord::Relation#blank?. Currently,
it calls `to_a` on the Relation, which loads all records in the
association, and calls `blank?` on the loaded Array. There are other
ways, however, to check the emptiness of an association that are far
more performant. `#empty?`, `#exists?` and `#any?` all attach a `LIMIT
1` to the SQL query before firing it off, which is a nice query
improvement. `#blank?` should do the same!

Bonus performance improvements will also happen for `#present?`, which
merely calls the negation of `#blank?`
Signed-off-by: NDavid Celis <me@davidcel.is>

Ignore activemodel/log/ folder

Fix some typos [ci skip]

Docfix: Use public interface instead of setting instance variables

Dynamically setting instance variables based on user input probably isn't a great idea. Better to go through the setter methods provided by attr_accessor.

Rather than raising ThrowResult when construct_limited_ids_conditions comes up empty, set the relation to NullRelation and rely on its results.

As we have moved to rails/docrails from lifo/docrails

Changing links to guides.

We are not worried for old versions as GitHub is 
handling the redirects.

Conflicts:
	railties/test/application/loading_test.rb

Add info about contributing to docs to CONTRIBUTING.md

Encourage more people to contribute to Rails docs by mentioning it in the contribution guide.

Fixing build for not checking migration

Need to pass parameters

Fixes #10432 add_column not creating array columns in PostgreSQL

Conflicts:
	activerecord/test/cases/adapters/postgresql/bytea_test.rb

Fix mismatching variable names when using an underscore

The ERBTracker template digest helper class was using a regex to match
render calls and it was incorrectly not matching against variables with
underscores in the name. This caused it to use the wrong regex match data
to populate the template dependency. Because underscore is a valid
character for a variable, this fixes the ERBTracker to match it properly.

Refactor ActionDispatch::Http::Parameters#normalize_encode_params