Wrap generated import headers using __OBJC__ for C only pods

Only use EMBEDDED_CONTAINT_CONTAINS_SWIFT on Swift <= 2.3

Greenify success message

Update to fourflusher 2

Allow passing --swift-version to pod spec/lib lint

Improve handling of mismatched Swift versions

Raises an Informative when a pod is shared between TargetDefinitions
that have different SWIFT_VERSION flags.

Removes duplicate entry in Changelog

Fix "does not update non-git repo" test

[Validator] Inform people of .swift-version on err

The test suggests that the fixture is a non-git repo when in reality it
is not. Seemingly, the `.git` file in there references a relative path,
but newer versions of git seem to make it absolute when cloning the
fixtures. This results in the copied repo being treated as a git repo
and the test failing. The fix just removes `.git` after copying, making
the fixture an actual non-git repo :)

Fix linting of private pods when using libraries