More work on ObjectStore.
Add dummy test git repository.

Add dummy test for objectstore.
Add writeObjecrt method in objectstore.
Add writeTree method to objectstore.
Cleanup objectstore test.
Build version 0.0.11
Add tests for git_util.

Addressed comments.
Merge pull request #206 from dart-lang/objectstore

More work on ObjectStore.
Add git_util test file.
Merge pull request #214 from dart-lang/objectstore

Add git_util test file.
Ability to convert git object to files.

This adds a way to write a git object tree into the filesystem.
Add todo for unittest.
Minor fixes (addressed comments).
Merge pull request #216 from dart-lang/object_util

Ability to convert git object to files.
Merge branch 'master' into test-chrome
review comments