change the put behaviour from asynchronous to sequential I/O.
add and convert logging code from java.util.logging to slf4j + logback
add and convert logging code from java.util.logging to slf4j + logback
add info log
change logging level from trace to debug.
parameter change the location of the log directory
changed the character encoding from sjis to utf-8
add slf4j and logback jar file to ant build file
add slf4j and logback jar file to .classpath file
modify number format of client response log
add native code and modify data disk manager to call native io methods.
add the synchronization flag of open(2)
remove unnecessary variable.
Merge branch 'refactoring_ykstorage_base'