Duration options are stored as null when creating or updating a policy

[bsushmith]

Description
On creating or updating a policy with appeal_config and duration_options configured, the resultant appeal_config value in the policies table is null. This is due to a mismatch between the proto definition expected value and the one in guardian docs.

based on Proton definition, code expects the field to be appeal, whereas based on guardian docs and json tags inside code expect it to be appeal_config. Modifying the json request body to have appeal instead seems to work.

Expected behavior
protos and guardian docs should be in sync.