Remove duplicated config types

Summary: This diff removes the `convertNewToOld` config method, which was only used by the unit tests (since there's no need to convert a new config object into an old one). As part of this, the config tests have been tweaked and simplified a bit, while keeping similar assertions and adding some more checks.

Reviewed By: mjesun

Differential Revision: D10015079

fbshipit-source-id: ba4fbd09cd4f97168bc1a2dbcec2699a00243637

package.json

@@ -185,7 +185,7 @@
     "opn": "^3.0.2",
     "optimist": "^0.6.1",
     "plist": "^3.0.0",
-    "pretty-format": "^4.2.1",
+    "pretty-format": "^23.4.1",
     "promise": "^7.1.1",
     "prop-types": "^15.5.8",
     "react-clone-referenced-element": "^1.0.1",