review costmap settings

[mgruhler]

Due to PR #66 some misconfigured costmap settings has been identified.
This will, however, be tackled in a seperate PR and should contain:

• Parameter map_type is outdated, needs to be removed. Is now configured in the plugins parameter via the ObstacleLayer or VoxelLayer. Maybe we need to change how/where this is configured...
• Adapt parameter for costmap scaling: inscribed_radius <= circumscribed_radius <= inflation_radius && cost_scaling_factor
• Check publish_voxel_map: this should only be true if we use a VoxelLayer
• Should we comment out the Voxel parameters if we don't use a VoxelLayer or configure them correctly for each robot?

@fmessmer FYI