A preliminary pass at number_with_delimiter

This is more to start a conversation as well as provide a possible
single concrete implementation for other things that might go into
Lotus::Helpers:

- I18n
- HTML Safe concerns
All those names will be hard to remember. What if we call them with a verb that reflects the name of module, plus the name of the of the subject?

Example:
```ruby

module Converters
  def convert_temperature
  end

  def convert_currency
  end
end
```