Add support of 'sudo -A' for privilege escalation

[Peter2121]

I am using Enlightenment WM with an internal helper for sudo (askpass method). Obviously, it is impossible to use octopkg as it cannot find neither kdesu nor gksu. Please, add support for askpass approach to octopkg.

[aarnt]

Upstream version uses its own sudo compatível tool. No need to 3rd party projects.