Config function

Implemented a new config function that lets you set the following properties on the player:

buffer - buffersize in seconds
scaleUp - specificies if the video can be scaled up or not
allowFullscreen - specifies if fullscreen mode is allowed or not.

Removed allowFullscreen function from api.
buffer doesn't seem to take effect when config is called. I think this needs to be client dependant. For RTSPClient for instance, closing the netstream and playing it again seems to trigger the buffering. This will most likely not work for HTTP or RTMP though. `IClient`could perhaps enforce implementation of some function `buffer` where the client attempts to fill the buffer.

Also, if play hasn't been issued, it will try to set `this.ns.buffer` to something, but `this.ns` is undefined at that point.