Add git clone.
Fix bug in expandTree.
Fix parsing bug in the git request.
Fix bug in sha / bytes conversion.
More work on git clone.
Add UI for git clone.
fix objectstore test.
nits.
Add placeholder test file for git clone.
Addressed comments
Merge branch 'master' into git_clone

Conflicts:
	ide/app/spark.dart
Merge pull request #379 from dart-lang/git_clone

Git clone