Toggle chevron direction

When editing a task, there are some expandable options available with a
chevron next to them (e.g. 'Tags' and 'Advanced Options'). This commit
makes the chevrons' directions toggle based on whether the related
option is expanded or collapsed, up and down respectively.

website/public/css/tasks.styl

@@ -441,6 +441,8 @@ form
         font-size: 0.75em
         content: "\E114"
         padding-left: 0.75em
+      &.active:after
+        content: "\E113"
     //&:not(.mega):after
       //content: ':'
 

website/views/shared/tasks/edit/advanced_options.jade

@@ -1,5 +1,6 @@
 div(ng-if='::task.type!="reward"')
   button.advanced-options-toggle.option-title.mega(type='button',
+    ng-class='{active: task._advanced}',
     ng-click='task._advanced = !task._advanced', tooltip=env.t('expandCollapse'))
     =env.t('advancedOptions')
 

website/views/shared/tasks/edit/tags.jade

@@ -1,5 +1,5 @@
 fieldset.option-group(ng-if='!$state.includes("options.social.challenges")')
-  p.option-title.mega(ng-click='task._tags = !task._tags', tooltip=env.t('expandCollapse'))=env.t('tags')
+  p.option-title.mega(ng-class='{active: task._tags}', ng-click='task._tags = !task._tags', tooltip=env.t('expandCollapse'))=env.t('tags')
   label.checkbox(ng-repeat='tag in user.tags', ng-if='task._tags')
     input(type='checkbox', ng-model='task.tags[tag.id]')
     markdown(text='tag.name')