(CFACT-86) Networking facts for solaris

This patch adds support for networking facts for solaris. This is patterned on
the bsd networking resolver. 

I agree that a general utility class should be in `facter::util` or `facter::util::posix` even if it's only (initially) used by Solaris. Otherwise, someone might come along working on non-Solaris and implement something similar elsewhere and we wouldn't get code reuse. (And btw, I fully imagine we'll be extracting some of the utility classes for use outside of facter altogether.)

@MikaelSmith re your idea, I'm torn as to whether that's over-abstracting or not. One concern is that we may not want uniform handling of system call errors (e.g. cases where we want to retry on EINTR/etc which is a mini-pattern). Of course we wouldn't be *obliged* to use this class in those cases, but it makes me wonder how general the abstraction is.

So at this point my leaning would be to move this up to `facter::util::posix` apply it to all (both?) `ioctl` uses in the code base and then, as our use of system calls increases over time, see if there's an opportunity for future abstraction.

I could be persuaded otherwise though, so comments welcome :)