(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 It would still be installed on windows machines for testing. As long as it doesn't require devkit (native extensions), it should be fine.