#20 Add tuner functionality

[Andres Colubri]

GStreamer-java exposes the tuner interface that allows to select one stream from a collection of streams originated by a software or a hardware tuner. This functionality could be useful to have in the GSCapture class.

Relevant references:
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/pwg/html/section-iface-tuner.html
http://code.google.com/p/gstreamer-java/source/browse/trunk/gstreamer-java/src/org/gstreamer/interfaces/Tuner.java
http://code.google.com/p/gstreamer-java/source/browse/trunk/gstreamer-java/src/org/gstreamer/example/TunerTest.java

Discussion on the Processing forum:
https://forum.processing.org/topic/gsvideo-any-way-to-add-crossbar-filter