.gml parsing (AJAX)

After looking at the codebase, I haven't found this because well, it's probably not something someone really should do, meaning that they should really port it to some other representation.

But it might help those moving from NetworkX to JSNetworkX to easily adopt. It also helps those who are more dependent on Gephi for network science. This also could mean that JSNetworkX could potentially build a browser based version of Gephi should this project grow that way.

I thought I'd just begin the discussion.