sound_play: say command only works for first user on the robot

[ahendrix]

For the 'say' command, soundplay_node.py creates a couple of files in /tmp, i.e. play_sound_text_temp.txt and play_sound_wave_temp.wav, but doesn't set their permissions to be non-owner writable.

Migrated from: https://code.ros.org/trac/wg-ros-pkg/ticket/3768