identity: Fix Expiry caveat input ux.

Remove clear date button from the date input.

Change-Id: I5b559c1b676fa560449154124f1432a8751fc8c4
diff --git a/services/identity/internal/templates/caveats.go b/services/identity/internal/templates/caveats.go
index 72caced..d5b8e3b 100644
--- a/services/identity/internal/templates/caveats.go
+++ b/services/identity/internal/templates/caveats.go
@@ -32,7 +32,7 @@
   <main class="add-blessing">
 
     <form method="POST" id="caveats-form" name="input"
-    action="{{.MacaroonURL}}" role="form">
+    action="{{.MacaroonURL}}" role="form" novalidate>
       <input type="text" class="hidden" name="macaroon" value="{{.Macaroon}}">
 
       <h1 class="page-head">Add blessing</h1>
@@ -226,6 +226,8 @@
 
     // Set the datetime picker to have a default value of one day from now.
     $('.expiry').val(moment().add(1, 'd').format('YYYY-MM-DDTHH:mm'));
+    // Remove the clear button from the date input.
+    $('.expiry').attr('required', 'required');
 
     // Activate the cancel button.
     $('#cancel').click(function(){