replace system call related to animated gif creation

[nathanfranklin]

https://github.com/simphony/AViz/blob/master/src/animationBoard.cpp uses a system call to run imagemagick's "convert" in order to create an animated GIF. This should be replaced. Related to #30

[nathanfranklin]

We should evaulate using a library such as Imagemagic, ffmpeg or gstreamer.