libvpx: new package at version 1.3.0

libvpx provides VP8/VP9 Codec SDK, "a high quality,
royalty free, open source codec deployed on millions
of computers and devices worldwide."

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
gst1-plugins-good: enable vpx enc/dec plugin

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Merge pull request #642 from luizluca/libvpx

Add libvpx and enable gst1-mod-vpx