Use LinkedHashSet to keep the insertion order for entries in the
Progress view. This way the most recent jobs are shown at the bottom of
the view and not somewhere else. Same for the error dialog showing
multiple job error entries.

Change-Id: I9a47d4913b30e584413c875c91fffd273e084872
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>