Fix for issue #27 - Do not show preview dialog if there is nothing
Fix for issue #27 - Do not show preview dialog if there is nothing

Description:
If there is nothing to download do not show the preview dialog.
Instead raise a message box informing that there is nothing to download.

Resolution:
Everything that depends on components (preview, download, etc)
is now skipped if there are no components to be downloaded.
SolidLeon/GenericLauncher