v1.4.0 seems to break validates numericality

Given this setup:
```ruby
class Foo < ActiveRecord::Base
  strip_attributes
  validates :foo, {
    numericality: {
      only_integer:             true,
      greater_than_or_equal_to: 1000
    },
    allow_blank: true
  }
end
```

In 1.3.0 I used to be able to do this:
```ruby
f = Foo.new
f.foo = 1000.1
f.valid? #=> false
```

Now it seems I get:
```ruby
f = Foo.new
f.foo = 1000.1
f.valid? #=> true
f.foo = 1000
```