Fixed naming of laser filter plugins in yaml files

[YoshuaNava]

This PR solves issue #69.

I just appended the prefix laser_filters/ to all the filter plugins call in this package yaml files.

[jonbinney]

@YoshuaNava thanks for this fix. I'll also forward-port it to the kinetic-devel branch.

[RohanDwivedi]

Hi, @YoshuaNava I installed the melodic branch of map_laser package from the ros melodic repo sudo apt-get install ros-melodic-map-filter which depends on this filter, yet the issue doesn't seem to have been resolved over there yet! Can I understand how that can be done?
update: fixed it, my bad, the yaml file in the package was not following the convention

wg-perception/people#103

[jonbinney]

@RohanDwivedi that's probably because this package hasn't been released on melodic since the fix was merged. So the source code in this repo has the fix, but the debian packages don't. Can you try cloning the indigo-devel version of this repo to your catkin workspace, recompiling, and see if that fixes the problem?