Rename launch files

Cleanup for nao_robot.
This involves removing several launch files in nao_description

Furthermore, launch files inside nao_apps are renamed. However,  please note that I only renamed the launch files. I did not rename python scripts in order to avoid wrong python imports.
@k-okada Could you please try the nao_apps folder before merging? I am not familiar with the code base inside of it.

thx