Cleans up HTML data attributes on body in default.hbs

closes #4485

- removes data attributes used on body in default.hbs
- introduces new way to generate configuration through meta tags
- config initializer consumes configurations from the meta tags using parser
- moves blog_title helper/value to be a property in a configuration api

ghost/admin/initializers/ghost-config.js

@@ -1,16 +1,11 @@
+import getConfig from 'ghost/utils/config-parser';
+
 var ConfigInitializer = {
     name: 'config',
 
     initialize: function (container, application) {
-        var apps = $('body').data('apps'),
-            tagsUI = $('body').data('tagsui'),
-            fileStorage = $('body').data('filestorage'),
-            blogUrl = $('body').data('blogurl'),
-            blogTitle = $('body').data('blogtitle');
-
-        application.register(
-            'ghost:config', {apps: apps, fileStorage: fileStorage, blogUrl: blogUrl, tagsUI: tagsUI, blogTitle: blogTitle}, {instantiate: false}
-        );
+        var config = getConfig();
+        application.register('ghost:config', config, {instantiate: false});
 
         application.inject('route', 'config', 'ghost:config');
         application.inject('controller', 'config', 'ghost:config');

ghost/admin/utils/config-parser.js

@@ -0,0 +1,36 @@
+var isNumeric = function (num) {
+        return !isNaN(num);
+    },
+
+    _mapType = function (val) {
+        if (val === '') {
+            return null;
+        } else if (val === 'true') {
+            return true;
+        } else if (val === 'false') {
+            return false;
+        } else if (isNumeric(val)) {
+            return +val;
+        } else {
+            return val;
+        }
+    },
+
+    parseConfiguration = function () {
+        var metaConfigTags = $('meta[name^="env-"]'),
+            propertyName,
+            config = {},
+            value,
+            key,
+            i;
+
+        for (i = 0; i < metaConfigTags.length; i += 1) {
+            key = $(metaConfigTags[i]).prop('name');
+            value = $(metaConfigTags[i]).prop('content');
+            propertyName = key.substring(4);        // produce config name ignoring the initial 'env-'.
+            config[propertyName] = _mapType(value); // map string values to types if possible
+        }
+        return config;
+    };
+
+export default parseConfiguration;