AV::Digestor thread safety fixes

This fixes potential thread safety issues introduced in 09f6fe1c. The problem
with the original code was that the "recursion-stopping" `nil` values could
be seen by other threads.

Remove cow => kine from default inflections but leave the test case
in place to prevent regression of the [old Trac ticket 4929][1].

[1]: http://web.archive.org/web/20090314050915/http://dev.rubyonrails.org/ticket/4929

Conflicts:
	activerecord/CHANGELOG.md

Add ability to specify how a class is converted to Arel predicate when passed to where

order on the old ones

The previous behavior added a major backward incompatibility since it
impossible to have a upgrade path without major changes on the
application code.

We are taking the most conservative path to be consistent with the idea
of having a smoother upgrade on Rails 4.

We are reverting the behavior for what was in Rails 3.x and,
if needed, we will implement a new API to prepend the order clauses in
Rails 4.1.

Update of 'The Asset Pipeline' guide for Rails 4.

Added Time#middle_of_day method

Add installation instructions for FreeBSD [ci skip]

interceptor should mimick original method

Fixing the broken URL [skip ci]

Add packages required to setup the rails environment on FreeBSD.

Use a lambda to ensure that the generated string respects the offset of
the time value. Also add DateTime#to_s(:iso8601) and Date#to_s(:iso8601)
for completeness.

use method with_active_record_default_timezone

Improved the doc about showing posts in getting started guide [ci skip]

- Reference #11644

remove duplicate method

This fix also makes the test order independent.

This method is already present in helper.rb

Add Time#to_s(:iso8601) for easy conversion of times to the iso8601 format for easy Javascript date parsing

grab executable from rubygems

Added middle_of_day method to Date and DateTime

This adds the ability for rails apps or gems to have granular control
over how a domain object is converted to sql. One simple use case would
be to add support for Regexp. Another simple case would be something
like the following:

    class DateRange < Struct.new(:start, :end)
      def include?(date)
        (start..end).cover?(date)
      end
    end

    class DateRangePredicate
      def call(attribute, range)
        attribute.in(range.start..range.end)
      end
    end

    ActiveRecord::PredicateBuilder.register_handler(DateRange,
      DateRangePredicate.new)

More complex cases might include taking a currency object and converting
it from EUR to USD before performing the query.

By moving the existing handlers to this format, we were also able to
nicely refactor a rather nasty method in PredicateBuilder.

This reverts commit 10259c3e.

reason: this causes rake test_mysql and test_mysql2 fail

Changed stylesheet load order in the stylesheet manifest generator.

Cleanup of class_name

fix order dependent test related to migration

make test order independent by resetting timezone

reset default timezone and make test order independent