sheep/config: init return value in init_config_file

Now ret is not initialized. Once config file is not existed, maybe
the return value of the function is not zero even if the new config
is created successfully.

Signed-off-by: Ruoyu <liangry@ucweb.com>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
shepherd: bugs fixed in shepherd_init

This patch fix some problems as below.

1. memory leak in error cases
2. when error occured, exit is tough, just return -1 is better
3. incorrect error message

Signed-off-by: Ruoyu <liangry@ucweb.com>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>