Add branch indicator for when behind master

When a repo's master branch has incoming changes and the repo is checked out to master, SmartGit displays the helpful down arrow indicator. But, if the repo is checked out to a non-master branch, there is no indicator for the branch-to-master status (as the indicators are for the checked out branch). To learn if a repo's master branch has incoming changes to update and rebase my working branch on, I have to click on each repo to review it. This requires reviewing the graph to find those commits and see how they align - is the branch missing commits from master.

The current product I'm working on has over 20 repos. To help this, perhaps an indicator on a branch in the Branches view when the branch is behind on its master branch?