Add hotkey shortcut for opening file location in explorer

It would be nice to have a shortcut for opening the file location in explorer. I work on projects that don't have particularly flat hierarchies, and the listview in sourcetree doesnt cut it (although the 1.6 changes help a lot--just still not as nice as a tree view) so I end up navigating in explorer a lot. It would be nice to have a shortcut like ctrl+e or ctrl+shift+e to open explorer on a file or set of files.