Use /assets for client assets

- Route `/assets` -> `build/public`, falling back on `public`
- Moved destinations for `nodebb.min.js`, `acp.min.js`, `admin.css`, `stylesheet.css`, `templates`, and `sounds` to `build/public`
- r.js modules previously routed through express are now symlinked into `public/build/src/modules`
- minfiles no longer served from a memory cache
- use config `views_dir` setting everywhere template directory is used
- fix cache buster `v=v=`

src/controllers/admin/settings.js

@@ -2,6 +2,7 @@
 
 
 var async = require('async');
+var nconf = require('nconf');
 var meta = require('../../meta');
 
 var settingsController = module.exports;
@@ -25,7 +26,7 @@ function renderEmail(req, res, next) {
 	var path = require('path');
 	var utils = require('../../../public/src/utils');
 
-	var emailsPath = path.join(__dirname, '../../../public/templates/emails');
+	var emailsPath = path.join(nconf.get('views_dir'), 'emails');
 
 	async.waterfall([
 		function (next) {