Added UI elements to add/remove Scenarios to various objects (#51)

Fixes #23

Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#51

templates/actions/objects/rule.html

@@ -3,4 +3,12 @@
         <a role="button" data-toggle="modal" data-target="#edit_rule_modal">
             <i class="glyphicon glyphicon-edit"></i> Edit Rule</a>
     </li>
+    <li>
+        <a role="button" data-toggle="modal" data-target="#set_scenario_modal">
+            <i class="glyphicon glyphicon-plus"></i> Set Scenarios</a>
+    </li>
+    <li>
+        <a class="button" data-toggle="modal" data-target="#delete_rule_modal">
+            <i class="glyphicon glyphicon-trash"></i> Delete Rule</a>
+    </li>
 {% endif %}