Indispensible packages installation optimized
list raw command added
The operations related to format command are refactoried

1. raw_hosts function added.
2. format_host function defined in common.sh
format --all command implemented
usage message udpated

1. rm -> rmcluster
2. ls --all added.
bug fixed on displaying cluster information
1. copy-ssh.ex, copy-ssh-first.ex moved to tools/
2. assign master operation added to registry.py.
3. validation for mkcluster command.
4. configure_master_host procedure separated from configure_hadoop_master procedure.
5. set command removed from usage.
6. syntax for mkcluster command changed: now can specify master host.
hadoop version updated: 1.2.1v -> 2.5.1
hadoop 2, zookeeper and merge command supported

1. hadoop version updated: 1.2.1 -> 2.5.1
2. zookeeper is supported.
3. merge command added.
4. automated os image id detection.