(FACT-698) Add fips_enabled fact

Adds a fips_enabled fact to determine if FIPS is enabled on the system.

FACT-698
the newer preferred way to do this in rspec is to do:

<pre>
expect(Facter.fact(:fips_enabled).value) to eq("true")
</pre>

That way we're not relying on rspec to monkey patch the object to contain a `#should` method. Lots of specs in puppet and facter still use the old way, but we're trying to not add new tests that use the old way.