add unit test of get the specific state disk ids.

implemented its test code and fake code.
add two method that retrieve spinning disk ids or standby disk ids.

commit with test code.
fake implement of RAPoSDACacheMemoryManager test.

Ticket 2
Implementing that the process, which to get the chunks on memories
corresponding to specific disk id.

The ticket 2 have closed.
Added BufferMonitor class to calculate mean arrival rate of write requests.

Ticket 3 is closed due to this commit.
add interface of buffermanager and buffermanager implementation for RAPoSDA.
add debug flag to Parameter.
add RAPoSDABufferManager. and change RAPoSDAStorageManager to use the buffer manager.

for bfa_tik_06
change the storage manager interface and the member access identifier from protected to public.

for bfa_tik_06
create EnergyEfficientBufferManager and its factory.

for bfa_tik_06
implemented energy efficient buffer manager. but need debug.

for bfa_tik_06
several changed.
Merge branch 'bug002' into bfa_tik06
buf fixed. and implemented bfa_tik_06
add buffer size command line argument
change log method level from debug to trace to avoid outout the unnecessary logs
addition the time of each disk state to the energy log.
change the log level from trace to info.
add timestamp information to the exception message.
add logginig code for debug of buffer flush behaviour.