Support unannotated single arg constructors as property creators

[WellingR]

This is a (partial) fix for #50 and follows the existing documentation which can be found on:
https://github.com/FasterXML/jackson-modules-java8/tree/master/parameter-names#delegating-creator:
If the module is registered as follows:

objectMapper.registerModule(new ParameterNamesModule(JsonCreator.Mode.PROPERTIES));

Then the given creator mode is used for constructors where no @JsonCreator annotation is used.

Includes the test from #31

I consider this a partial fix, because having this as default behaviour would be better, see FasterXML/jackson-databind#1498

[cowtowncoder]

Thank you. I'll have to see if I can figure why behavior is/was the way...

I'd have to merge this in 2.11 since I expect change here to break someone's usage, just because this area is notoriously brittle. :)

[WellingR]

Rebased against 2.11

[cowtowncoder]

Um, I don't think this makes sense: override was designed to simply allow specifying PROPERTIES vs DELEGATING mode for @JsonCreator that omitted mode. Change would basically make every constructor (and static factory method) visible without annotation: this would not work well either functionally or from security perspective.

[cowtowncoder]

@WellingR first of all: thank you for your contribution. I realized that in its current form this would unfortunately not work (as per comments), but that I can probably figure out an alternative that would.
Since this is a long-time request, I will go back and try to get the issue itself fixed for 2.11.

[WellingR]

Thanks for figuring this out. I already was sort of doubting whether fixing this was really this simple.