Remove deprecated Array#uniq_by and Array#uniq_by!

Use native Array#uniq and Array#uniq! instead.

activesupport/CHANGELOG.md

+*   Remove deprecated `Array#uniq_by` and `Array#uniq_by!`, use native
+    `Array#uniq` and `Array#uniq!` instead.
+
+    *Carlos Antonio da Silva*
+
 *   Remove deprecated `ActiveSupport::BasicObject`, use `ActiveSupport::ProxyObject` instead.
 
     *Carlos Antonio da Silva*

activesupport/lib/active_support/core_ext/array.rb

 require 'active_support/core_ext/array/wrap'
 require 'active_support/core_ext/array/access'
-require 'active_support/core_ext/array/uniq_by'
 require 'active_support/core_ext/array/conversions'
 require 'active_support/core_ext/array/extract_options'
 require 'active_support/core_ext/array/grouping'

activesupport/lib/active_support/core_ext/array/uniq_by.rb

-class Array
-  # *DEPRECATED*: Use <tt>Array#uniq</tt> instead.
-  #
-  # Returns a unique array based on the criteria in the block.
-  #
-  #   [1, 2, 3, 4].uniq_by { |i| i.odd? } # => [1, 2]
-  def uniq_by(&block)
-    ActiveSupport::Deprecation.warn 'uniq_by is deprecated. Use Array#uniq instead'
-    uniq(&block)
-  end
-
-  # *DEPRECATED*: Use <tt>Array#uniq!</tt> instead.
-  #
-  # Same as +uniq_by+, but modifies +self+.
-  def uniq_by!(&block)
-    ActiveSupport::Deprecation.warn 'uniq_by! is deprecated. Use Array#uniq! instead'
-    uniq!(&block)
-  end
-end

activesupport/test/core_ext/array_ext_test.rb

@@ -359,36 +359,6 @@ def test_extract_options_extracts_hwia
   end
 end
 
-class ArrayUniqByTests < ActiveSupport::TestCase
-  def test_uniq_by
-    ActiveSupport::Deprecation.silence do
-      assert_equal [1,2], [1,2,3,4].uniq_by { |i| i.odd? }
-      assert_equal [1,2], [1,2,3,4].uniq_by(&:even?)
-      assert_equal((-5..0).to_a, (-5..5).to_a.uniq_by{ |i| i**2 })
-    end
-  end
-
-  def test_uniq_by!
-    a = [1,2,3,4]
-    ActiveSupport::Deprecation.silence do
-      a.uniq_by! { |i| i.odd? }
-    end
-    assert_equal [1,2], a
-
-    a = [1,2,3,4]
-    ActiveSupport::Deprecation.silence do
-      a.uniq_by! { |i| i.even? }
-    end
-    assert_equal [1,2], a
-
-    a = (-5..5).to_a
-    ActiveSupport::Deprecation.silence do
-      a.uniq_by! { |i| i**2 }
-    end
-    assert_equal((-5..0).to_a, a)
-  end
-end
-
 class ArrayWrapperTests < ActiveSupport::TestCase
   class FakeCollection
     def to_ary