Should raise a warning/error or something when methods already exist

[thornomad]

class MyClass < ApplicationRecord
  def blue?
    'blue!'
  end

  enumbled_to :color
end

my = MyClass.new(color: Color.blue)
my.blue? #=> true (not "blue!")

The Enumbler will just silently overwrite a method that is already defined. Rails has a nice way of warning you when it is overwriting a method. We should do the same.

[thornomad]

This was partially fixed by #7 (which addressed an enabled model). This needs to be extended to work with enumbled_to models.