Finished release v0.1.3.

* release/v0.1.3:
  another fix in _retreive_properties
  a better handling of possible None return value from collector.RetrievePropertiesEx
  EsxCLI: changing the MMESoapStubAdapter.versionId to the ESX api version, not the vSphere API version - they can be different
  handling possible None return value from collector.RetrievePropertiesEx