Prevent scroll up when click on links in sharing dropdown

When clicking on a link that points to "#" in the sharing dropdown, and
the current view is scrolled down, the browser will scroll the page up
to the top (anchor behavior).

This fix cancels the click event when clicking on "unshare" link or
"show crud" link.

core/js/share.js

@@ -502,6 +502,7 @@ $(document).ready(function() {
 
 	$(document).on('click', '#dropdown .showCruds', function() {
 		$(this).parent().find('.cruds').toggle();
+		return false;
 	});
 
 	$(document).on('click', '#dropdown .unshare', function() {
@@ -519,6 +520,7 @@ $(document).ready(function() {
 				$('#expiration').hide();
 			}
 		});
+		return false;
 	});
 
 	$(document).on('change', '#dropdown .permissions', function() {