fork & pull request
updated GitRepository's fork and merge to use the 'file://' rather than 'http://'
refactoring and testing fork&pull request

- added CloneAndFetchTemplate to reduce duplicated codes in GitRepository.
- added some tests for GitRepository and CloneAndFetchTemplate.
Merge pull request #69 from keesun/HIVE-142

HIVE-142 포크&풀리퀘 기능 구현