First of all I think there is a need for adding the installation process to the readme file as the user needs to download an engine. Even I Think adding some description about different engines to the file will make things very easy and clear.

Anyway my problem is that i have downloaded the "qrencode" but cannot set it's path.
I'm working on my localhost. I have copied the engine to the "/sites/all". but setting this path as of "/sites/all/qrencode" is not working.

Am I missing something here?