Disable debug messages from Qt when Release build is made

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
Remove unused connection

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
Changelog update

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
Merge pull request #178 from vogel/fix-169

Fix 169