Add branch exceptions.
Add getRemoteBranch api to objectstore.
Add creating from a remoteBranch api to scm.
SUpport remote branches in git branch.
switch to a remote branch.
Merge branch 'master' into remote_branch

Conflicts:
	ide/app/lib/git/commands/clone.dart
	ide/app/lib/git/exception.dart
Fetch a remoteHead on creating a new branch.
cleanup.
Remove todo in http_fetcher.
Create branch past fetching.
Add more custom exceptions.
move uint8list types to list<int>
Merge branch 'master' into remote_branch
Merge branch 'master' into remote_branch

Conflicts:
	ide/app/lib/git/commands/status.dart
optimize update index.
Merge branch 'master' into remote_branch
fix broken commit and create branch dialog.
Merge branch 'master' into remote_branch
Merge branch 'master' into remote_branch
Merge branch 'master' into remote_branch