Allow ctags to be run anywhere

This requires changing the drush bootstrap level to DRUSH_BOOTSTRAP_DRUSH since
we can't rely on a Drupal install being present.
Merge branch 'ctags-anywhere'

* ctags-anywhere:
  Allow ctags to be run anywhere
Adds console script for drupal 8
Merge branch 'console8'

* console8:
  Adds console script for drupal 8