Unify name of LeoFS's processes

[yosukehara]

• We are difficult to recognize the LeoFS's processes on Erlang's console.

[yosukehara]

• DONE
  • https://github.com/leo-project/leo_logger/commit/af34bc7a8a5ef18e8f2e54036108dfc8c1ebbf39
  • https://github.com/leo-project/leo_statistics/commit/521d3603e589bfbefeaacf059b288c97575f689b
  • https://github.com/leo-project/leo_storage/commit/601e036a74688ad6661745d12f80f24b91d15fd2
  • https://github.com/leo-project/leo_object_storage/commit/7457591fec198694228c92b3ad36dc9d7ffcc25e