Create deterministic test data

[nickevansuk]

Test data generation should create deterministic data for a particular day, with deleted records created for ideas created from the previous 7 days, using the same deterministic algorithm. When the data is generated it must use modified dates from the current day.

This will make it resilient to night reboots, any data user harvesting the records will be able to accurately keep track of reboots.

Also add a warning that bookings made and tokens generated may be erased due to system reboots.