Detect IO errors in save
Remove unnecessary logs
Devide open error and read/write error
Detect IO error in load
Remove incomplete file
Add warning message when failed to remove
Fixed wrong message
use uint64_t instead of size_t to prevent overflow (#692)
Merge pull request #710 from jubatus/fix-692

use uint64_t instead of size_t to prevent overflow (#692)
Merge pull request #698 from rimms/fearute/detect_ioerrors

Detect IO errors in save
Add stdio.h include for remove (3) function: refs #698