fix(card): action bar spacing, remove order attrs

Card sections use DOM source order rather than flex order.
This makes it so that an action bar can go in between content and the footer, and have any number of combinations.

Closes #2403. Closes #2412.

src/components/card/card.scss

@@ -12,16 +12,21 @@ md-card {
 
   > img,
   > :not(md-card-content) img {
-    order: 0;
     width: 100%;
   }
 
   md-card-content {
-    order: 1;
     padding: $card-padding;
   }
+  md-action-bar {
+    margin: 0;
+
+    .md-button {
+      margin-bottom: $card-margin;
+      margin-top: $card-margin;
+    }
+  }
   md-card-footer {
-    order: 2;
     padding: $card-padding;
   }
 }

src/components/card/demoBasicUsage/index.html

@@ -12,6 +12,10 @@ <h2 class="md-title">Paracosm</h2>
           two most important words in Ernest Greene's musical language: feel it. It's a simple request, as well...
         </p>
       </md-card-content>
+      <md-action-bar layout="row" layout-align="end center">
+        <md-button>Action 1</md-button>
+        <md-button>Action 2</md-button>
+      </md-action-bar>
     </md-card>
 
     <md-card>