This merges functionality that was previously stored in the
combination of PBGitCommitController / PBChangedFile to a
dedicated controller, PBGitIndexController.
This adds a div in the webview to display the current commit
state. It allows us to notify the user of new commits by
showing something in the webview, rather than a modal
dialog.
This causes trouble if a file was partially staged,
or if we switch from the staged changes to the
unstaged changes.
It should be quick enough not to matter anyway, so
let's simplify things and remove the check.
Pieter de Bie