gvfs-move: Fix cmd-line help and error reporting
gvfs-move: Fix cmd-line help and error reporting

Partly fixes bug #593045
halfline/gvfs,gicmo/gvfs,gicmo/gvfs,xkahn/gvfs-cmis,xkahn/gvfs-cmis,gicmo/gvfs,philipl/gvfs,halfline/gvfs,cpatulea/gvfs,halfline/gvfs,gicmo/gvfs,xkahn/gvfs-cmis,philipl/gvfs,cpatulea/gvfs,philipl/gvfs,xkahn/gvfs-cmis