Fixed misspelled help message in cfg.py
Fixed misspelled help message in cfg.py

Reasons:
- Help message for exists_notification_ticks has misspelled
  reference to report_intevals.

Changes:
- Corrected report_intevals to report_intervals.

Change-Id: Iac13298a5f1a9fa938283982a9e52455c0ef0ae9
Closes-Bug: #1267822

zhujzhuo/openstack-trove,changsimon/trove,zhangg/trove,denismakogon/trove-guestagent,mmasaki/trove,fabian4/trove,zhujzhuo/openstack-trove,zhujzhuo/openstack-trove,cp16net/trove,fabian4/trove,redhat-openstack/trove,mmasaki/trove,cp16net/trove,changsimon/trove,openstack/trove,cp16net/trove,fabian4/trove,changsimon/trove,redhat-openstack/trove,mmasaki/trove,denismakogon/trove-guestagent,openstack/trove,hplustree/trove,hplustree/trove,zhangg/trove,redhat-openstack/trove