Include total as attribute or header

[aaronjoslyn]

It would be great to be able to get the total number for a given model when requesting a page from the index:

generalized_api/lib/generalized_api/api.rb

Lines 10 to 16 in 093ea7b

	def index
	query = resource.where(permitted_params).order(order_params).paginate(pagination_params)
	yield query if block_given?
	query = filters(query)
	body = {resource_key.pluralize => query}
	render_processed_entity(body)
	end