Support customizing the composer below the textarea

app/assets/javascripts/discourse/templates/composer.hbs

@@ -101,6 +101,7 @@ so I'm going to stop rendering it until we figure out what's up
 
         {{#if currentUser}}
           <div class='submit-panel'>
+            {{plugin-outlet "composer-fields-below"}}
             <button {{action "save"}} tabindex="5" {{bind-attr class=":btn :btn-primary :create disableSubmit:disabled"}} title="{{i18n 'composer.title'}}">{{{model.saveIcon}}}{{model.saveText}}</button>
             <a href='#' {{action "cancel"}} class='cancel' tabindex="6">{{i18n 'cancel'}}</a>
           </div>

app/assets/javascripts/discourse/views/composer.js.es6

@@ -73,6 +73,13 @@ var ComposerView = Discourse.View.extend(Ember.Evented, {
       if (pos) {
         self.$('.wmd-controls').css('top', $fields.height() + pos.top + 5);
       }
+
+      // get the submit panel height
+      pos = self.$('.submit-panel').position();
+      if (pos) {
+        self.$('.wmd-controls').css('bottom', h - pos.top + 7);
+      }
+
     });
   }.observes('model.composeState', 'model.action'),