Dev

I added a tests file to test `merMod` objects. I also added some changes to the model.info for `merMod` objects to include some basic information about the group effects. I think this works pretty well for multiple effects at each level (slope and intercept) and multiple levels of effects. I haven't tested all edge cases, but take a look and see what you think. 

I don't know how to improve the `stars` -- it seems to me like for now the best advice is to set `lev=0` and then `apsrtable` works fine for `merMod` objects -- it just excludes the stars. 

I also added a .gitignore file.