Includes these changes:
- Modified so that IPv6 CIDRs can be converted correctly.
- Added test cases for IPv6 addresses.
- Split UTs for hexCIDR() and asciiCIDR() so that masking can be tested.
- Add UTs for failure cases.

Note: Some code that calls hexCIDR() builds a CIDR from the pod IP string
and the concatenation of "/32". These should, in the future, use "128",
if/when the pod IP is IPv6. Not addressed as part of this commit.