Update Truth to use the newer TestRule and fix a few minor things.

anyOf(Integer first, Integer second, Integer... rest) - this just guaranteed that the third null wasn't being passed in as an Integer[].  Standard varargs issue.  We can expand out the thing, and under the hood, I interpret a null as a null item, not a null array, even if it's passed in as a null array, simply because there is no universe in which passing in a null array makes sense in this api.  But it quiesced a warning.