Add Category and Multicategory to axis types.

Author: Jim Hague

src/partials/tab_display.html

@@ -145,6 +145,8 @@ <h5 class="section-heading">{{axis.label}}</h5>
           <option value="linear">Linear</option>
           <option value="log">Log</option>
           <option value="date">Date</option>
+          <option value="category">Category</option>
+          <option value="multicategory">Multicategory</option>
         </select>
       </div>
     </div>