Added support for unit tests to CMake

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>
Added kdevelop files to .gitignore

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>
Added support for custom user.cmake file with example

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