Summary:
This will allow kwin to grant permission to powerdevil which no other
application should have. Previously used kded module is now replaced by
the application which installs in LIBEXEC dir and started by desktop
file in /etc/xdg/autostart

Test Plan: Restarted session, powerdevil starts and all functions work perfectly

Reviewers: graesslin, broulik, #plasma

Reviewed By: broulik, #plasma

Subscribers: davidedmundson, shumski, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D2372