Add Java 8 generics support

[mailmindlin]

When writing applications to recieve data from a camera, it would be nice to be able to utilize some of the nice Java 8 things.

For convenience, it would be nice to have a method on FrameGrabber like setCaptureCallback(Consumer<VideoFrame>, Consumer<V4L4JException>). V4L4J would lose compliance with Java 7, but that would occur for almost all of these ideas.

Another way to update is to support streams (i.e., Stream<VideoFrame> FrameGrabber#videoStream()). The major caveat is the undefined behavior upon an exception, and Stream is hard to implement.

[mailmindlin]

Added FrameGrabber#setCaptureCallback(Consumer<VideoFrame>, Consumer<V4L4JException>) in dc00bb3.