formated log message
add log message
 * failed to start
modify exception message
* keeper could not find any servers
modify save/load function's log
 * use jubatus::exception::error_file_name to print file path
 * print message instead of only e.what()
add start message for save/load functions (fixed #195)
modify server's log messages
 * failed to start
format server's log
 * add debug log to insert/update/remove operation.
 * move clear function's log to last of method.
 * add name to clear function's log.
 * and more...
fixed typo
move set_config log to end of method
commonize log (anomaly)