Simplify jobset cloning

We can just show the normal "edit jobset" page for the original jobset
and then do a PUT request to create a new jobset.

Also simplified updating the jobset inputs.  We can just delete all of
them and recreate them from the user parameters.  That's safe because
it's done in a transaction.

src/root/edit-project.tt

@@ -56,7 +56,7 @@
     <div class="form-actions">
       <button id="submit-project" type="submit" class="btn btn-primary">
         <i class="icon-ok icon-white"></i>
-        [%IF create %]Create[% ELSE %]Apply changes[% END %]
+        [%IF create %]Create project[% ELSE %]Apply changes[% END %]
       </button>
     </div>