Adding documentation to the Rails initialization guide. [ci skip]
Simplify/fix implementation of default scopes

The previous implementation was necessary in order to support stuff
like:

    class Post < ActiveRecord::Base
      default_scope where(published: true)
      scope :ordered, order("created_at")
    end

If we didn't evaluate the default scope at the last possible moment
before sending the SQL to the database, it would become impossible to
do:

    Post.unscoped.ordered

This is because the default scope would already be bound up in the
"ordered" scope, and therefore wouldn't be removed by the
"Post.unscoped" part.

In 4.0, we have deprecated all "eager" forms of scopes. So now you must
write:

    class Post < ActiveRecord::Base
      default_scope { where(published: true) }
      scope :ordered, -> { order("created_at") }
    end

This prevents the default scope getting bound up inside the "ordered"
scope, which means we can now have a simpler/better/more natural
implementation of default scoping.

A knock on effect is that some things that didn't work properly now do.
For example it was previously impossible to use #except to remove a part
of the default scope, since the default scope was evaluated after the
call to #except.
find_in_batches should work without logger
Remove order_values argument now that default_scope is simplified

In 94924dc32baf78f13e289172534c2e71c9c8cade the internal default_scope
implementation has changed making it simpler to follow, meaning that the
old usage of with_default_scope has been removed.

With that, order_values was the same argument for both calls to
find_first_with_limit, so remove it and use the existent attribute
for the sake of clarity/simplification.
Omit turbolinks configuration completely on skip_javascript generator option
Merge pull request #11161 from dmitry/find_in_batches_works_without_logger

ActiveRecord find_in_batches should work without logger

When I set logger to nil both methods from Batches module find_in_batches or find_each should work anyway.
Merge pull request #11163 from nfedyashev/omit_turbolinks_on_javascript_skip_option

Omit turbolinks configuration completely on skip_javascript generator option
Merge pull request #11160 from wangjohn/documentation_for_railties_initialization_guide

Adding documentation to the Rails initialization guide.
writing the new body can cause the response to be committed and the
request thread to return up the stack before the instance variable is
assigned.  Synchronize so that the ivar is assigned before the other
thread can activate.

fixes #10984
use bytesize rather than force encoding
remove deprecated implicit join references.
fetch value(s) from stringified options
Update a broken link into the fixtures' template
Merge pull request #11175 from robin850/patch-4

Update a broken link into the fixtures' template [ci skip]
Merge pull request #11152 from senny/remove_implicit_join_references

remove deprecated implicit join references
provide a more sementicthe local variables name for ActiveModel::Validations::Clusivity#include? method
the original name `exclusion` is a bit confusing when using with the method `inclusion_method`
rename it to a more logic neutral name.
Merge pull request #11156 from JonRowe/fix_tags_picking_string_keys_from_non_stringified_options

Fetch value(s) from stringified options in tags that stringify options
Merge pull request #11177 from yangchenyun/mine

provide a more sementic local variables name in ActiveModel::Validation::Clusivity
Fix `rails plugin --help`

Right now if you run the `rails plugin --help` command it fails because rails expects a command in `railties/lib/rails/commands/plugin.rb` that does not exist because the file is named `plugin_new`. This is the error:

```
ruby-2.0.0-p0  ~/documents/projects/tmp/vanilla (master)
$ rails plugin --help
/Users/schneems/.rvm/gems/ruby-2.0.0-p0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:228:in `require': cannot load such file -- rails/commands/plugin (LoadError)
	from /Users/schneems/.rvm/gems/ruby-2.0.0-p0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:228:in `block in require'
	from /Users/schneems/.rvm/gems/ruby-2.0.0-p0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:213:in `load_dependency'
	from /Users/schneems/.rvm/gems/ruby-2.0.0-p0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:228:in `require'
	from /Users/schneems/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0/lib/rails/commands.rb:49:in `<top (required)>'
	from bin/rails:4:in `require'
	from bin/rails:4:in `<main>'
```
Merge pull request #11176 from schneems/schneems/plugin_new_help_fix

Fix `rails plugin --help`