Automatic syncing option

When the input directory is in VOSpace, there is now the option to have automatic syncing of results files back to VOSpace.  This option is toggled through the Sync menu.  The Sync menu is disabled when working on a local directory.

Synchronization occurs in threads to minimize the performance impact on the rest of the system.  Results files become available for syncing as soon as they are finished being written to.

Note that the VOSpace directory that results are synced to is the input directory, not the optional output directory.  The output directory should still be the local area where you want to keep results files, and then either manually or automatically copy back to VOSpace.

Closes #104