slim: make the first item in sessions always an empty default

This solution is specific to lunar and authored by me.
It is much less intrusive than all the patches I looked at.

However, if a user doesn't handle an empty session parameter
in his ~/.xinitrc script and starts a default in this case,
this (first) entry will break down and he will have to select a
different one.
mplayer2: Depends on Python-3
Merge branch 'master' of github.com:lunar-linux/moonbase-other
xbmc: bump to 13.1
freshplayerplugin: adding to zbeta for the brave of heart desiring to
shirk thy shackles of flash. It is in alpha so could cause a tear in
some part of reality you care about.
libconfig: adding to zbeta only because it is a depends for freshplayerplugin
mockcpp: adding to zbeta, a depends for freshplayerplugin
uriparser: adding to zbeta, depends for freshplayerplugin
Merge pull request #328 from v4hn/slim-default-session-support

slim: make the first item in sessions always an empty default
libg2o-git: initial import to moonbase
VTK: added to moonbase
pcl: initial import to moonbase
fcl: introduction to moonbase
armadillo: introduction to moonbase
epos2_motor_controller: initial import to moonbase
OpenNI: initial import to moonbase

I can't say I have a running kinect over here,
but at least all software depending on OpenNI compiles fine with this...
rospkg: initial commit for rospkg
catkin_pkg: initial import to moonbase
rosdistro: initial import
rosinstall: initial import