Remove some opendap code that found its way into the grib module.

I have no idea how it got there.  Must have pasted the wrong thing while
working on multiple changes.
Force int32 arrays for timeaxiscore.get_indices.

This used to be the case, but the code was removed in a recent update.

I was assuming that the numpy C API can handle the casting from 64-bit to
32-bit integers, but it was throwing an error about the types.  The equivalent
call from Python works fine, however.