Bug 441760 - Allow Enums to be added to and getBinary from JsonArray

Fix for bug 441760 for 2.x branch:
After switching to from Vertx 2.0.2 to 2.1.2 it was not possible anymore to add an Enum value to the JsonArray.
Please add back support for adding an Enum value.

In a JsonArray, a byte[] is stored in a Base64 encoded way, but it is only possible to retrieve the value as a String. Application should not need knowledge on the internals of Vertx so please add a method to get a binary value from the JsonArray.