Fix DBus issues with the launcher script and fix LD_LIBRARY_PATH.

7f93b61 Fixes DBus issues #59 and #97.
It's an adaptation of the fix proposed by fcarlier in #59.

0e965c1 Fixes an issue with LD_LIBRARY_PATH discovered by @popcornmix.
If you have a bad lib in the current directory it will be included if your LD_LIBRARY_PATH is empty.
This is because LD_LIBRARY_PATH currently resolves to "/opt/vc/lib:/usr/lib/omxplayer:" causing to include the current directory because it ends in ":". This fix avoids to include non-existing LD_LIBRARY_PATH env var.

This fixes are already working on the launcher script I use for my packages.