Updated code with proper status message and finished callback, also ensured empty form is displayed when there are no content types or no aliasable content types with appropriate messages linking to the respective settings. Ran updates through coder module.
@todo add some valid code in case of error to provide some insight in case the batch api fails
@todo add a install file with hook_uninstall for deleting the module specific variables as suggested in Review tips on https://drupal.org/node/1187664
@todo consider breaking up the code chunks to their own inc files, perform code review with smoke testing once done
@todo consider improvising module functionality to choose between aliasing all nodes and un-aliased ones
@todo also consider providing an aliasing option for taxonomy terms and users if possible or sounds logical