Remove usage of _neitherNull on findProperty

[deblockt]

Remove usage of _neitherNull on findProperty to get custom property if possible.

close #1912

[cowtowncoder]

Thank you for contributing this. Looks legit.

But would it be possible to get a unit test, to show the effect, and guard against regression? (... by refactoring such as the one that broke handling).

[cowtowncoder]

One other minor thing: I'm happy to merge this, but one thing we need before the first contribution to Jackson projects is CLA: (unless we already got one -- apologies if I missed earlier one, tried to check)

https://github.com/FasterXML/jackson/blob/master/contributor-agreement.pdf

Usual way is to print, fill, sign, scan & email toinfo at fasterxml dot com.
There is also alternative Corporate CLA if you prefer, most contributions are under individual one.

[deblockt]

@cowtowncoder I will add unit test.

I have see that master is under 3.0.0-SNAPSHOT version.
If I want this bug to be fixed on the next version of Jackson, which branch should I merge on? Is it 2.9 branch?

[cowtowncoder]

I'd guess this was done for 2.9, so branch would be 2.9, which is easy to merge to master then.
I can handle backporting if need be.

So I just need the CLA, whenever you get a chance (it's just one time thing, not needed for further contributions. But needed since big corporations want to ensure all code contributions are done properly wrt licensing etc).

Thank you again!