Update KotlinModule to override AnnotationIntrospector.findCreatorAnnotation() instead of hasCreatorAnnotation()

[cowtowncoder]

AnnotationIntrospector method hasCreatorAnnotation() was deprecated in 2.9, in favor of more powerful findCreatorAnnotation(); and in 3.0 former will be removed.
Since I just upgraded master to be for 3.0, this causes compilation error, but even in earlier versions it would be better to use newer method as it can express actual intent better and perhaps even help solve an open issue or two.

I can help with semantics as necessary, but unfortunately my Kotlin skills are not good enough for me to actually provide patch for this yet.

As to where to fix: I am guessing that although fix for 2.9 might be nice, it'd go in 2.9.9, and probably it's good enough to fix that in 2.10, and it should merge ok to master.

[TjeuKayim]

I touched that method in my pull request for inline classes, and also noticed that it was deprecated.
Should I fix this in #205 if I'm working on it anyway? Or do you like to fix it in a separate pull request?

[cowtowncoder]

@TjeuKayim I think @apatrida can give definite answer to the question, but to me it seems fine to do that change within existing PR.