Have freebsd port use pkg info if the freebsd version is >= 10000017

The port package provider for FreeBSD was not checking if the freebsd version is version 10. This causes the provider to attempt to use 'pkg_info' instead of 'pkg info'. This PR should fix this bug.
@btm I have updated the package/provider to use supports_pkgng? provided by the package. I noticed that with the initial test setup, node was nil due to the run_context not being passed in. Is this an actual concern?