vm init fails parsing hostonlyifs output

[aldafu]

This is on Win 8.1.

The error is:

Boot2Docker init
error in run: Failed to initialize machine "boot2docker-vm": strconv.ParseUint:
parsing "128": value out of range

The output that needs to be parsed includes:
IPV6NetworkMaskPrefixLength: 128

That value is then parsed by this code:

boot2docker-cli/virtualbox/hostonlynet.go

Line 103 in cb4be2b

l, err := strconv.ParseUint(val, 10, 7)

strconv.ParseUint(val, 10, 7) will fail when val is 128.

bit size should be increased to 8.