sheep: print PACKAGE_VERSION with SDOG_INFO log level

Signed-off-by: Kai Zhang <kyle@zelin.io>
Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
minor: clean code in ops.c

Signed-off-by: Kai Zhang <kyle@zelin.io>
Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>