Revert "Adding a hook to store emojis in db dynamically."

This reverts commit 47eb5880.

lib/rumoji/emoji.rb

 # -*- encoding: utf-8 -*-
-
-require 'rumoji/mixin'
-require 'rumoji/extensions'
-
 module Rumoji
   class Emoji
 

lib/rumoji/extensions.rb

-class ApplicationRecord
-  def self.stores_emoji_characters(*attributes)
-    return unless table_exists?
-
-    Rumoji::Mixin.inject_methods(self, attributes)
-  end
-end
\ No newline at end of file

lib/rumoji/mixin.rb

-module Rumoji
-  module Mixin
-    def self.inject_methods(model, attributes)
-      attributes.each do |attribute|
-        model.class_eval <<-RUBY, __FILE__, __LINE__ + 1
-          before_save do
-            unless respond_to?("#{attribute}=")
-              raise ArgumentError.new('#{model} must respond to #{attribute}= in order for Rumoji to store emoji.')
-            end
-
-            self.#{attribute} = Rumoji.encode(self.#{attribute})
-            true
-          end
-
-          def #{attribute}
-            Rumoji.decode(super)
-          end
-        RUBY
-      end
-    end
-  end
-end
\ No newline at end of file