Website update + clean build system

Introduced by the video branch

After intalling the libraries libgsm1 and libgsm1-dev, you can create the shared library codec_gsm.so with:
gcc -shared -o codec_gsm.so gsmcodec.cpp -lgsm

This code captures the video from a webcam (v4l2, cf doc/sflphone_video) and display it as a texture on an openGL window