Add additional files to data folder

Add the logrotate and Xsession.d script for ck-launch-session to
the data folder so it's easier for distros to include it. These
files were pulled from the Debian ConsoleKit package:
http://ftp.de.debian.org/debian/pool/main/c/consolekit/consolekit_0.4.6-5.debian.tar.xz