Cronicle: authenticated users can inject environment variables into job processes

Cronicle is a multi-server task scheduler and runner, with a web based front-end UI. Prior to 0.9.124, an authenticated non-admin with run_events, create_events, or edit_events privilege can supply undeclared keys in event params through api_create_event, api_update_event, or api_run_event. lib/api.js and lib/api/event.js validate the parameter object without restricting its keys, and lib/job.js uppercases those keys and applies them to the child process environment after administrator-defined plugin variables. A key that collides with a security-sensitive environment variable can therefore override the plugin execution context and may cause privilege escalation, arbitrary code execution, data access, or service disruption depending on the plugin and runtime. This issue is fixed in version 0.9.124.