#908964 alex_b: Break out scheduler. Note: Features depends on Job Scheduler module now: http://drupal.org/project/job_scheduler .

Use existing() for ensuring that the importer in question actually exists in DB or in code. Plus one minor cleanup in switch statement.

  scheduled tasks than 'import' and 'expire'.

This is a preemptory step to enable cleaner result handling and prepare the ground for Batch API use.