add some fancy form-field features to select demo

Author: mmalerba

src/demo-app/select/select-demo.html

@@ -14,6 +14,9 @@
           {{ drink.viewValue }}
         </md-option>
       </md-select>
+      <md-icon mdPrefix class="demo-drink-icon">local_drink</md-icon>
+      <md-hint>Pick a drink!</md-hint>
+      <md-error>You must make a selection</md-error>
     </md-form-field>
     <p> Value: {{ currentDrink }} </p>
     <p> Touched: {{ drinkControl.touched }} </p>

src/demo-app/select/select-demo.scss

@@ -7,4 +7,8 @@
     margin: 24px;
   }
 
+  .demo-drink-icon {
+    vertical-align: bottom;
+    padding-right: 0.25em;
+  }
 }