First spin for an universal way to run ettercap as root by pkexec

Fix for issue #49
Changes for make it work.

Build ettercap with gtk enabled.
copy ettercap to ettercap.elf in the bin directory
copy desktop/ettercap in your bin directory
edit desktop/org.pkexec.ettercap.policy by manually changing the executable path
copy desktop/org.pkexec.ettercap.policy /usr/share/polkit-1/actions/org.pkexec.ettercap.policy

(you need to install prior polkit)

Please give me feedback about this and please tell me how to make it work with cmake :)
I know how to deal with this in debian, but I'm not a cmake guy