Added 8 tests for issue #1489, one of which is failing. The failing test...

... reproduces the issue that @jomnius reported with the < version operator. One of the passing tests checks the question that @alloy asked about using ~> with a pre-release version. The other passing tests verify correct behavior with the other version operators when dealing with pre-release versions.

After further investigation, this looks like it will have to be fixed in Core, probably in dependency. I think it would still be good to have these tests at the CocoaPods level, though.