Prevent querying for double-underscored properties accessed by Python internals.
Merge branch 'python_26_length_hint_support'
Release 0.4.post1; adds fix for Python 2.6.

* Merges currently-uncommitted PR fixing VersionOne's behavior on
  Python 2.6.  See https://github.com/versionone/VersionOne.SDK.Python/pull/18
  for more details.