Add kwargs to jsonutils.load(s) functions

Now jsonutils.load(s) doesn't allow to pass additional params to
underlying json.load(s) (such as 'parse_int' or 'cls').  This patch adds
kwargs to jsonutils.load(s) that are passed to json.load(s).

Change-Id: I9b032e6047b207ad3af14dadd90f207e3a9ca0e5
Merge "Add kwargs to jsonutils.load(s) functions"