(FACT-695) Return correct data types

Fix the processorcount, physicalprocessorcount, \*\_mtu, is_virtual,
selinux, mem\*\_mb, swap\*\_mb and sp\_\* facts for return the correct data
types. Mostly integers or booleans instead of strings.
@dalen @ferventcoder last year when I looked at it, json-schema didn't support windows. So in puppet's Gemfile I ended up with: https://github.com/puppetlabs/puppet/blob/3.7.0/Gemfile#L41-L44