CI: Descriptively name each Sauce invocation

Also, attach .customData.build_url to screenshot invocation, to match
unit tests

circle.yml

diff --git a/circle.yml b/circle.yml
index d9c2766..2c766b8 100644
--- a/circle.yml
+++ b/circle.yml
@@ -140,6 +140,7 @@
            -u $SAUCE_USERNAME:$SAUCE_ACCESS_KEY \
            -H 'Content-Type: application/json' \
            -d '{
+                 "name": "Unit tests, Mocha",
                  "build": "'"$build_name"'",
                  "customData": {"build_url": "'"$CIRCLE_BUILD_URL"'"},
                  "framework": "mocha",

script/screenshots.js

diff --git a/script/screenshots.js b/script/screenshots.js
index a22e34c..516c366 100644
--- a/script/screenshots.js
+++ b/script/screenshots.js
@@ -78,6 +78,8 @@
 
 browsers.forEach(function(browser) {
   browser.config.build = build_name;
+  browser.config.name = 'Visual tests, ' + browser.config.browserName + ' on ' + browser.config.platform;
+  browser.config.customData = {build_url: process.env.CIRCLE_BUILD_URL};
   var browserDriver = wd.promiseChainRemote('ondemand.saucelabs.com', 80, username, accessKey);
   return browserDriver.init(browser.config)
   .then(function(args) {