LILY-206: Remove referrers to big objects (analyzed with `meminspect`) and force call to garbage collect.
Remove `rusage.ru_maxrss` prints in tasks.
Fix not clearing `query_count`, `total_query_string` and `param_list` for batch jobs.
Added pympler and psutil to requirements (used by lily's meminspect and celery's sample_mem).
Add celery to newrelic
LILY-206: Add maxtasksperchild and autoscale arguments for the dyno 'worker1'
Fix mail sync in task 'retrieve_new_emails_for', prevent deleting emails not matched by CRITERIA from ALLMAIL every time.
LILY-206: Change IronMQ host to EU
Merge branch 'hotfix-memory-management-206' into develop