Ros handler

[ayonix]

Things done:

• Ported the world description to sdf version 1.4/1.5
• Changed defaults to turtlebot instead of pr2 (had no time/intent to test this)
• Removed the pr2 actuator handler (should be readded and fixed if pr2 is to be used)
• Instead of copying files to some fixed location we use the current folder of the handler to create/change the world and things, thus we don't need the installer

Things working:

• Using gazebo2 with ROS indigo, a specification and LTLMoP generated map/world

Things to do:

• Fix pr2? (I won't have time for this)
• Obstacles are a bit weird (in the demo they are kind of overlapping)
• Find a better way than to use the handler folder
• Don't change the xml/sdf files, rather read the string and manipulate that only
• Don't use regular expressions to change the xml/sdf files
• Don't use stdbuf to force line buffering (needs the coreutils on linux systems)

Quick demo:

The pull request closes #87