Remove Dir.chdir for thread safety.
Add chdir option to native commands in status.
Fix invalid byte sequence errors when using grep method
git 1.7.4.6 required.

The following tests failed with git 1.7.2.1

* grit/test/test_commit.rb:201
* grit/test/test_repo.rb:422

The minimum version passing tests is 1.7.4.6
Merge pull request #23 from babatakao/patch-1

git 1.7.4.6 required.
Merge pull request #22 from jacargentina/fix-utf8

Fix invalid byte sequence errors when using grep method
Correct version with gem
Merge branch 'no-chdir' of https://github.com/xdissent/grit into xdissent-no-chdir
Fix packed-refs parse after PR #13
Remove last chdir for thread safety
Version up to 2.6.0
Merge branch 'master' of https://github.com/gitlabhq/grit