littlechef.runner: make sure to define `env.sync_packages_dest_dir` and
`env.sync_packages_local_dir` when using littlechef as library
Merge pull request #205 from tobami/lib_sync_packages_param

littlechef.runner: make sure to define `env.sync_packages_dest_dir` and `env.sync_packages_local_dir` when using littlechef as library