Continued const-correctness improvement from Scott McKellar:

Continued const-correctness improvement from Scott McKellar:

1. I changed the signature of jsonObjectDecodeClass so that it accepts
a non-const pointer parameter.  Since it doesn't change the contents
of the jsonObject, there's no need to confine it to non-const
jsonObjects.

2. I replaced jsonObjectGetKey() with jsonObjectGetKeyConst().

3. In one spot I captured the return value of jsonObjectGetIndex()
with a const pointer instead of a non-const pointer.

git-svn-id: svn://svn.open-ils.org/OpenSRF/trunk@1095 9efc2488-bf62-4759-914b-345cdb29e865