Updated the grib api to v1.12.1

FYI @dkillick
As it stands, this gets NumPy v1.7.1, which is a downgrade from what Iris installs:
```
The following packages will be DOWNGRADED:

    numpy:      1.8.2-py27_0       --> 1.7.1-py27_2 
```

This means that importing Iris fails after installing this package:
``` 
File "numpy.pxd", line 861, in init scipy.special._ufuncs (scipy/special/_ufuncs.c:21822)
ValueError: numpy.ufunc has the wrong size, try recompiling
```

Could this be bumped to also get v1.8.2?