Commit through web UI commits other users' staged changes

[isc-pbarton]

If two different users have changes staged on a multi-user development environment, and one user does a commit through the web UI, that will commit all staged changes. It's not clear that all changes will be committed because only the changes owned by the current user show up in the Staging Area section of the UI.

[isc-tleavitt]

Ultimately I'd love to see "staging" replaced by a system of checkboxes like in GitHub desktop.