Remove or update CSS zoom property

[JoeGermuska]

Via Zendesk, we received this request:

as Firefox warns, please change the css »zoom:1« to «transform:scale(1);transform-origin: 0 0«

zoom is not a standard CSS property, so this change should be made.

All references to the zoom property seem caught up in very old IE support, and in some cases, use "the star hack". They should probably simply be removed rather than updated to use transform

StoryMapJS/source/less/map/leaflet/VCO.Leaflet.IE.less

Line 31 in 34d8150

zoom: 1;

StoryMapJS/source/less/core/Mixins.less

Line 117 in 34d8150

*zoom: 1;

StoryMapJS/source/less/core/Reset.less

Line 46 in 34d8150

*zoom: 1;