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

##### COMPONENT NAME

~~~

~~~

##### CLOUDSTACK VERSION

~~~

~~~

##### CONFIGURATION

##### OS / ENVIRONMENT

##### SUMMARY

##### STEPS TO REPRODUCE

~~~

~~~

##### EXPECTED RESULTS

~~~

~~~

##### ACTUAL RESULTS

~~~

~~~

首先比较 marvin/lib/util.py 中的 format_volume_to_ext3 与 marvin/sandbox/demo/simulator/testcase/libs/utils.py 中的重复实现。搜索 marvin 的 Python 代码，查找其他重复的方法，并确定哪些实现应当保留。完成的标准是：在不改变现有行为的情况下合并重复实现。

由索引模型根据 Issue 内容生成。