Refactor - adding different scala object detecting

[marcinbelicki]

I'm adding ScalaObject along with ScalaObjectTest to detect whether given Class[_] is a scala singleton object. I'm not sure if clazz can be a null but I'm adding Option(clazz) in ScalaObjectDeserializerResolver just in case.

[pjfanning]

build fails with

[info] com.fasterxml.jackson.module.scala.ScalaObjectMapperTest *** ABORTED ***
[info]   java.lang.InternalError: Malformed class name
[info]   at java.lang.Class.getSimpleName(Class.java:1330)
[info]   at com.fasterxml.jackson.module.scala.util.ScalaObject$.unapply(ScalaObject.scala:27)

[marcinbelicki]

I've corrected clazz.getSimpleName to clazz.getName - I wasn't aware that classes from inside of scala singleton objects cant produce propper simple name :/

[pjfanning]

@marcinbelicki I've started #657 - I may grab more of the changes in this PR but there I don't like all the new classes in this PR

[marcinbelicki]

Ok, I see your point

[pjfanning]

@marcinbelicki #657 is merged and will appear in v2.16.1 release - thanks for driving this