methods implemented twice in marvin code

in the marvin python code some methods are implemented twice.
example:
format_volume_to_ext3(ssh_client, device="/dev/sda") in `marvin/lib/util.py` and in `marvin/sandbox/demo/simulator/testcase/libs/utils.py`

more can surely be found.

##### ISSUE TYPE

* Bug Report
* Improvement Request
* Enhancement Request
* Feature Idea
* Documentation Report
* Other

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##### CONFIGURATION

##### OS / ENVIRONMENT

##### SUMMARY

##### STEPS TO REPRODUCE

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##### EXPECTED RESULTS

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##### ACTUAL RESULTS

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先比較 marvin/lib/util.py 中的 format_volume_to_ext3 與 marvin/sandbox/demo/simulator/testcase/libs/utils.py 中的重複實作。搜尋 marvin 的 Python 程式碼，找出其他重複的方法，並判斷哪些實作應予保留。完成的標準是：在不改變現有行為的情況下整合重複的實作。

由索引模型根據 Issue 內容生成。