Repository View: Add Directory Tree Hierarchy option

Currently multiple repositories are organized by manually arranged groups on the "Local Repositories" tab. For my multi-repo workflow, I usually end up working with several clones clustered in directories that have all their dependencies together for an active task. This means that I might have multiple `foo` clones in various commit states on my disk. Because of this, it is often hard for me to tell which `foo` repo corresponds to which directory with the current SmartGit multirepo management system.

Rather than having things manually arranged into groups, it would be helpful to have a button that just sorts all the SmartGit-tracked repositories into collapsible file trees that match the directory structure on disk. This would be independent of the current manually user-defined groups which I can see as having distinct logistical value for some workflows.

Originally, I thought that this was how it worked, because on first install, that was how all the manual groups were configured. However, subsequent repository additions have required me manually dragging the files in the right place. This is kind of tedious, especially if I batch clone a bunch of repos from the command line and want to add them later into SmartGit.

If this proves too invasive to have independent options, I would be satisfied with an automated solution to sort the manual groups to match the directory structure. 

Loving SmartGit, by the way! Such a huge improvement over SourceTree!