Prior to the Related-Change, non_negative_int would raise a ValueError
if it was passed a positive float. It now casts the float to an int,
which is consistent with the docstring.
This patch adds test assertions to verify this behavior, and similar
behavior of config_positive_int_value.
Change-Id: I5d62e14c228544af634190f16321ee97a8c4211c
Related-Change: I06508279d59fa57296dd85548f271a7812aeb45f
e984de864d