Add option to translate footer ({activeView} of {totalViews})

[Bastian]

Steps to reproduce the behavior:
/

Expected behavior:
It would be nice to be able to change the footer text (currently hardcoded: {activeView} of {totalViews}) without replacing the whole Footer component.

react-images/src/components/Footer.js

Lines 112 to 117 in 89ba278

	<Span
	css={getStyles('footerCount', props)}
	className={className('footer__count', state)}
	>
	{activeView} of {totalViews}
	</Span>

Actual behavior:
The only option to change the text (as far as I can see) is to override the Footer component. It would be more convenient to have it included in the already existing formatters object:

react-images/src/formatters.js

Lines 66 to 74 in 89ba278

	export default {
	getAltText,
	getNextLabel,
	getPrevLabel,
	getNextTitle,
	getPrevTitle,
	getCloseLabel,
	getFullscreenLabel,
	};