API: Delete hook has different calling convention than other resources

Created by: Xylakant

Deleting a hook uses DELETE /api/v3/project/:project_id/hooks with a json payload of the form {hook_id: 1}. All other DELETE calls use DELETE /api/v3/<resource>/:resource_id with an empty payload, e.g. removing team membership uses DELETE /api/v3/projects/:project_id/members/:member_id. This is a bit confusing, all operations should follow the same calling conventions.