dashboard next: minor tweaks

* help texts
* renaming of components to dashboard-*
* use number formatter
* adjust trend position

app/assets/javascripts/admin/components/dashboard-mini-chart.js.es6

@@ -3,7 +3,7 @@ import computed from 'ember-addons/ember-computed-decorators';
 import loadScript from 'discourse/lib/load-script';
 
 export default Ember.Component.extend({
-  classNames: ["mini-chart"],
+  classNames: ["dashboard-mini-chart"],
 
   classNameBindings: ["trend", "oneDataPoint"],
 

app/assets/javascripts/admin/components/dashboard-mini-table.js.es6

@@ -2,7 +2,7 @@ import { ajax } from 'discourse/lib/ajax';
 import computed from 'ember-addons/ember-computed-decorators';
 
 export default Ember.Component.extend({
-  classNames: ["mini-table"],
+  classNames: ["dashboard-mini-table"],
 
   total: null,
   labels: null,