Flexible time intervals on Logging Reports

I'm finding that the logging reports are not good at showing changes made through a batch process as they assume a very short time interval and that only one contact will be affected in a change.

This proposed change just changes the underlying code to allow a flexible time interval & to return the contact_id where it has been retrieved so that the code is more useful to alternative reports

https://github.com/fuzionnz/civicrm/commit/372c53880b153200894f8b0ff45cd78c6460abba