fetch districts with ajax GET for speediness

‘POST requests are never cached’.

http://blog.httpwatch.com/2009/08/07/ajax-caching-two-important-facts/

It does seem like this can speed up loading the districts from 3-5 seconds, when using POST, to a couple hundred milliseconds, when using GET. You can see this by looking at Chrome’s dev console -> ‘network’
tag and observing a page load.