Re-factor properties method/ivar into class variable

[krainboltgreene]

Source TODO marker:

def check_properties_of(values)
  # Go over each key, and if it results in false raise an ArgumentError
  raise ArgumentError unless values.each_key.all? do |property|
    # Check to see if the property is included in the class property list
    # TODO: Raise properties into a class variable
    self.class.properties.include? property
  end
end