Drop v1 code to simplify things.
Fix permissions on install.
Update and fixurls: use functions from civicrm.drush.inc instead of duplicating the code (now possible since we use the version-specific civicrm.drush.inc from civicrm.)
_provision_civicrm_upgradedb: show the upgrade output as a warning. Most civicrm upgrades show instructions that the user should read.
drush_civicrm_post_provision_verify: Fix for the function call to drush_civicrm_cacheclear().