Add a retention to evidence

[Lowmanio]

The ability to add a custom retention period for the evidence. Once met, to email the custodian that the evidence can be removed / destroyed etc.

Perhaps also a custom time period where after a case is closed it is automatically archived?

[Lowmanio]

https://bitbucket.org/lowmanio/foreman/commits/616f8380955b59312fcf6082763b8ccc0c1de1e5

Evidence now has 4 statuses: inactive (before and after its been worked on), active, archived and destroyed. There is no difference in Foreman between archived and destroyed (both do not allow editing of evidence). Admins can set a retention period in months and can run a script in CRON or Windows task scheduler to check and email out on a daily basis.