Updated build instructions for Ubuntu

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>
Disable qMake builds on Linux

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>
Add -gstabs paramter to compiler

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>