Blueprint fixes

[jasonvarga]

Resolves #2144 by fixing an incompatible config array being passed along to reference fields.

We build an array of the field's configs, and when you click a field, that array gets passed up to the server via ajax.
It's preProcessed on the server. The error was happening because we preprocessed it twice - once when building the initial array, and again when it's passed up to the server. Once upon a time, we may have needed it processed up front but looks like it hung around unintentionally when we changed the approach.

The issue was in toBlueprintArray() - it was only used in the core in two spots:

• One of them was in an old unused controller, so I deleted that as well as the related fieldtype.
• The array mentioned above. Instead of using toBlueprintArray, I just inlined the appropriate keys needed. It was passing in more than necessary anyway.

The name toBlueprintArray is unintuitive, so I've deprecated it and just left it alone. Anyone using it (I only see one non-core use on all of GitHub, by @duncanmcclean).