Renamed 'imageformat' property to 'pixel-format', and set default to 'auto',
which will query the camera for supported PixelFormats, then allow
GStreamer to negotiate the format with downstream elements.
Merged from https://github.com/zingmars/gst-pylonsrc
This includes some changes to include running gst-indent, and
modification to allow it to compile with Visual Studio 2012/VC11.