Housekeeping routine - Delete claims

[tomwm]

Contents of the claims are deleted:

• 12 months after submission (in submitted state) or;
• 18 months after start date (in created state), if not submitted.

Claim number is persisted so that it cannot be re-used.

[dan-palmer]

I wrote the code to start this off(extract the claim reference number into its own table so its easier to keep around after the actual details are removed) however we had a number of issues when running the specs sometimes. This needs investigating first.