Improve the remember me feature

Signed-off-by: Johanna Mantilla Duque <johanna1431@gmail.com>
Check manage_options instead of edit_plugins for display the pluggin
settings page

This change fix the error reported by users when try to config the
plugin: "You do not have sufficient permissions to access this page."

The error happen when the WordPress site has disables plugin and theme file editing, by
adding define('DISALLOW_FILE_EDIT', TRUE); on wp-config.php
Signed-off-by: Johanna Mantilla Duque <johanna1431@gmail.com>