run.php should only be used for running behat
before this patch if tags were passed, then behat.yml
was being re-written with features havings tags.
As this is not ideal, this option is now removed and
features with tags will be optimally split
by init.php when --optimize-run option is passed
if theme/tests/behat/behat_theme_{THEME_NAME}_behat_selectors.php
file exits, and has class with same file name then we will
call behat_theme_{THEME_NAME}_behat_selectors::register_moodle_selectors()
to register theme specific selectors. If they are different
then core then they will override
Rajesh Taneja