Install application without Google Play
Normally phones should be able to install apps even if they are not signed. Normally your friend should be able to install your app. I was able to download the application, and I could also start the installation from the link.

Make sure that your friends phone has 'unknown sources' enabled in the security menu (enable Settings > Security > Unknown Sources). Because otherwise it will also not work (without using Google Play == unknown source).

No offense though, but I didn't test all the way through the installation, because I don't trust it well enough and I have no idea what the app actually does. For all I know it is a virus ;-)