Expose per-page size picker for grids

tailbone/templates/grids/buefy.mako

@@ -160,7 +160,21 @@
 
     % if grid.pageable and grid.pager:
     <template slot="footer">
-      <div class="has-text-right">showing {{ firstItem }} - {{ lastItem }} of {{ total }} results</div>
+      <b-field grouped position="is-right">
+        <span class="control">
+          showing {{ firstItem }} - {{ lastItem }} of {{ total }} results,
+        </span>
+        <b-select v-model="perPage"
+                  size="is-small"
+                  @input="loadAsyncData()">
+          % for value in grid.get_pagesize_options():
+              <option value="${value}">${value}</option>
+          % endfor
+        </b-select>
+        <span class="control">
+          per page
+        </span>
+      </b-field>
     </template>
     % endif