feat(client/js/handler.s3.xhr): #897 - set policy expiration date to 5 minutes from "now"
chore(utils): allow qq.each to iterate over chars in a str
test(test/unit/util.js): more qq.each tests, add tests for qq.getExtension
feat(client/js/handler.s3.xhr.js): #897 - pass custom params w/ S3 upload request, encode special chars