fsync destination directory after file renames

Conflicts:
	src/tools/file_system.ml
always copy through a temporary file

Conflicts:
	src/node/dump_store.ml
	src/node/local_store.ml
	src/tools/file_system.ml
feedback related to fsync_dir argument
fsync directory of newly created tlog files
Merge pull request #220 from Incubaid/copy-temp-file-and-fsync

Copy temp file and fsync