Use plugins for costmap instead of pre-Hydro

[Tiryoh]

またcostmapの使用がHydroから大きく変わっていて、パラメーター設定の方法がpre-Hydro形式と最新の形式があります。pluginsというパラメーターがないとpre-Hydro形式になって色々なパラメーターを良しなに内部で設定してくれます。ネットで調べるとpre-Hydro形式が多く出てくるのですが、最新の形式のほうが詳細に設定をすることができるのでこの方式を説明します。

ref: https://qiita.com/srs/items/fba2c83b96d17b2680e6

Pre-Hydro Parameters
Hydro and later releases use plugins for all costmap_2d layers. If you don't provide a plugins parameter then the initialization code will assume that your configuration is pre-Hydro and will load a default set of plugins with default namespaces. Your parameters will be moved to the new namespaces automagically. The default namespaces are static_layer, obstacle_layer and inflation_layer. Some tutorials (and books) still refer to pre-Hydro parameters, so pay close attention. To be safe, be sure to provide a plugins parameter.

Plugins
~/plugins (sequence, default: pre-Hydro behavior)

Sequence of plugin specifications, one per layer. Each specification is a dictionary with name and type fields. The name is used to define the parameter namespace for the plugin. See the tutorials for examples.

ref: http://wiki.ros.org/costmap_2d/layered