ACF 5.3.1 support

[radist2s]

I implemented full support for ACF 5.3.1, and it should work for previous ACF versions.

[mrwweb]

@radist2s Thank you! I'm testing this just now and it's mostly working. So far I've found a few issues:

1. No single-row collapse for block layout
2. Single row collapse doesn't work in row layout repeater nested in block layout
3. No "collapse all rows" for flexible fields

This does seem close, so I'd love to put out your changes if you can fix these issues.

I'm hoping for a bigger rewrite sometime in the next year to improve the nested-repeater collapsing, but for now, this fix is greatly appreciated. Thank you!

[jesserosenfield]

Just made some basic fixes for ACF 5.4.4 by updating class names in the CSS and JS files
https://github.com/jesserosenfield/ACF-Repeater-Collapser

Thank you @mrwweb !!!