Minor bug fix for shell scripts in sandbox directory

[lpstudy]

(#897)

1. deploy.sh: extra x in "$1"x == "master_slave". Also add -h option which is common in linux shell scripts.
2. start_bfs.sh: bfs can not work well with raft mode enabled with only sleeping 5 seconds, add 'sleep 30' when using raft mode.
3. start_bfs.sh: cd - print the working directory which is useless. Add the server starting message like start nameserver0 with pid xxx.
4. clear.sh: redirect the error log message like process not found to /dev/null. It does no good but confuses the users.

[CLAassistant]

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