Preliminary Addition of CosmoSim Simulation Database Query Tool

This it my first pull request of the addition of simulation datbase query tools to astroquery. As it stands, things are in rough shape, but I welcome all comments, concerns, and tips. Thanks!
Could you find a way to get this wrapped to 80 characters? It might help to store some of these things - e.g. `data['databases'][i['name']` - in a shorter variable above, for example