AJAX in shape data vs. inlining

[rdmurphy]

Currently the Texas page is really chunky because we're in-lining the entire geoJSON file. This doesn't bite us too hard on other pages because the districts are pretty simple shapes. But this one is huge. We could get a sizable cache benefit if that was instead AJAX'ed for Google Maps to use — or at a minimum loaded via its own file that can pick up the cache header.