re-implement ManualScheduler, and use it as the scheduler.

1. becasue AutoScheduler can not use NWR correctly. we choose the
ManualScheduler as the replacement.
2. because ManualScheduler can not adjust order of the hosts, I
re-implement it.
3. becuase ManualScheduler need more detailed configure file, i change
the config format from ini to yaml.
4. do some optimize for reduce cpu time.
5. ErrorLog path is specified in config file, replace old design: stderr.
   fixing: rotating log maybe make some log missing.
6. Bugfix: delete a not-exist key while a back node down, alway return
server error.
refactoring: make open accesslog and errorlog in a function.
add the missing log.go
implement the reopen log file's logical in log.go
change interface from Storage to DistributeStorage
fix bug: change default conf from example.ini to example.yaml
remove SIGSTP trap code.
test1
add down host to test1
fix cmd stop
close log file fd while shutdown.
Merge pull request #1 from ningan/beanseye:delete_bear_softstate

简单的test1
make signal trap works.
add debug make target to Makefile
init stats in scheduler's initializa function.
fix a index out of slice panic
fix test1, add test set should fail
add test2 for test case with temporary node
fix test2 (previous understand about failover is not correct), add delete test
Merge pull request #2 from ningan/beanseye:delete_bear_softstate

fix和增加两个test