Remove delete_email task, this is already covered by delete_inboxen_item

Closes #28
Speed up batch deletes

Batch deletes don't happen fast enough and multiple tasks get spawned
for the same orphaned items. This helps that somewhat, however it is not
a long term fix.
Fixed test breakage from last commit - will still error due to celery bug
Turn down frequency of scheduled tasks
Ignore broken tests for the moment
Merge branch 'master' into deploy