soundplay_node crashes after running for an extended period (ros ticket #7)

[ahendrix]

From experience, the soundplay_node crashes after running for an extended period of time.

Poking at it a bit more, it appears to be leaking open file descriptors, and when it hits the OS limit of 1024 open file descriptors, it's unable to create or play sounds and crashes.

trac data:

• Owner: ahendrix
• Reporter: ahendrix
• Reported at: Wed Sep 5 15:14:45 2012
• URL: https://kforge.ros.org/audiocommon/trac//ticket/7

[ahendrix]

[ahendrix] gst objects weren't being properly garbage-collected because they weren't stopped when cache objects were deleted. Added a destructor for cache objects that fixes this.

Fixed in commit 98.