This adds a new dock to the main window that contains all the remote
functionality (or is supposed to contain it all in the future).
It also adds a directory browsing feature which allows you to browse
through the folders and files on the dbhub server.
By double clicking a database you can download and open it. The Open
Remote menu action isn't needed anymore and has been removed.
This also fixes an issue with pushing databases where, after sending the
file is completed, the save dialog was opened.
Note that this is still WIP and is far from polished.
