adding NPM dependency badge to readme

Uses the david-dm.org service.
add CodeClimate badge to readme

related to issue #440
Update Google Analytics tracking code to Universal Analytics.
Migrate event tracking to use analytics.js
Change @streetmixapp to @streetmix twitter handle on scripts.js
Merge pull request #448 from codeforamerica/twitter

Change @streetmixapp to @streetmix twitter handle on scripts.js
Merge branch 'master' into announce-migration-downtime