Ignore more installed versions of python during tests
Ignore more installed versions of python during tests

The unit tests for python_dir fact were giving a false failure

```
1) python_dir is empty string if python not installed
   Failure/Error: expect(Facter.fact(:python_dir).value).to eq('')
     expected: ""
          got: "/usr/lib/python2.7/site-packages"
     (compared using ==)
```

If they were executed on a system where `/usr/libexec/platform-python`
was present - not the case (presumably) for Travis CI.

voxpupuli/puppet-collectd,voxpupuli/puppet-collectd,voxpupuli/puppet-collectd