Remove validates_timeliness

This library has been abandoned, has been producing deprecation warnings and is only used to validate a single field so remove it and perform the validation ourselves.

This is of arguable value but the deprecation warnings were annoying me. Also, the validator is only tested by the model specs.

Any opinions?
I don't know the code convention but, if you want, you can use the ActiveSupport::Autoload and remove the file path. This line is fine anyway, but I just showing other way to do it, =):

```ruby
  module Validators
    extend ActiveSupport::Autoload
    autoload :DateOfBirth
  end
```

That's it.