Little refactor and add transition support

* Drops non-standard `border-radius` support.
* Adds generalized value flipping for vendor-prefixed versions of properties that need value flipping.
* Isolates the property-flipping and value-flipping logic.
* Adds support for flipping of supported properties found in values of `transition` and `transition-property` (inc. vendor-prefixed versions - see above).

cc @brettstimmerman