BUG: fix score, add score_factor and score_obs

I think you should be able to just merge this into your branch

fixes score and adds related methods

the script and example I used to check the results is below
I put `score_check` in there as method to make the comparison between analytical and finite difference score easier.

Also, I got tired of figuring out the diag version of the score and switched to a non-diag version right away.
`score_factor` has two 1-D components

```
import numpy as np

from statsmodels.miscmodels.betareg import Beta

from statsmodels.miscmodels.tests import test_beta as tb

income = tb.income

model = "I(food/income) ~ income + persons"

mod = Beta.from_formula(model, income)
rslt = mod.fit()

#print(rslt.summary())

print('\nscore')
print(mod.score(rslt.params))
print(mod.score_check(rslt.params))

print(mod.score(rslt.params * 1.2))
print(mod.score_check(rslt.params * 1.2))
print(mod.score_obs(rslt.params * 1.2).sum(0))
```