fetcher: add is_running method

Signed-off-by: Young-Ho Cha <ganadist@gmail.com>
schedule: improve scheduler

print schedule is registered and unregistered
avoid cross reference

Signed-off-by: Young-Ho Cha <ganadist@gmail.com>
main: update various improvement

add TimeSyncManager for time sync monitor
refactor FetcherService

Signed-off-by: Young-Ho Cha <ganadist@gmail.com>