Remove list id option on logout and display signup form only when we have list selected in settings.

Author: iamdharmesh

mailchimp.php

@@ -217,7 +217,7 @@ function mailchimp_sf_request_handler() {
 				}
 
 				// erase auth information
-				$options = array( 'mc_api_key', 'mailchimp_sf_access_token', 'mc_datacenter', 'mailchimp_sf_auth_error', 'mailchimp_sf_waiting_for_login', 'mc_sopresto_user', 'mc_sopresto_public_key', 'mc_sopresto_secret_key' );
+				$options = array( 'mc_api_key', 'mailchimp_sf_access_token', 'mc_datacenter', 'mailchimp_sf_auth_error', 'mailchimp_sf_waiting_for_login', 'mc_sopresto_user', 'mc_sopresto_public_key', 'mc_sopresto_secret_key', 'mc_list_id' );
 				mailchimp_sf_delete_options( $options );
 				break;
 			case 'change_form_settings':
@@ -1403,5 +1403,5 @@ function mailchimp_sf_get_access_token() {
  * @return bool
  */
 function mailchimp_sf_should_display_form() {
-	return mailchimp_sf_get_api() && ! get_option( 'mailchimp_sf_auth_error' );
+	return mailchimp_sf_get_api() && ! get_option( 'mailchimp_sf_auth_error' ) && get_option( 'mc_list_id' );
 }