rename gst-launch --> gst-launch-1.0
replace old elements with new elements(ffmpegcolorspace -> videoconvert, ffenc_** -> avenc_**)
fix caps in examples
https://bugzilla.gnome.org/show_bug.cgi?id=759432
No need to call gst_remove_silence_reset() in gst_remove_silence_init() because
vad_new() already calls this function. Since there are no more uses of
_silence_reset(), we can remove it altogether.
