update gstreamer version to 1.0 in archlinux install scripts

What I've done with the Archlinux install scripts:

* updated GStreamer to 1.0
* moved gstreamer-ffmpeg to install_deps script to make it more like the ubuntu scripts (the ffmpeg package is called gst-libav on arch)
* added gstreamer gst-plugins-base explicitly to install_deps script

Tested this on Archlinux 64bit with all old gstreamer packages removed beforehand.

this refs 56caffc011ac2d8ed8c7b30d628aaf0429d704c3