Relogit - model-fitting function bug

Using `cbind` as part of the formula for a `relogit` model seems to not work.

`z.out <- zelig(cbind(suc, nosuc) ~ loc, model="relogit", data=myData)`

Data:

```
  loc         suc     nosuc
0 0.0000000   5       493064
1 0.6931472   2       68832
2 1.0986123   0       5741
3 1.3862944   0       609
```
