Create 2.4 branch, update master to be for 2.5.0-SNAPSHOT
Updates for 2.5.x and adding an implied JsonCreator when it is appropriate.
Slight update to README
Update README.md
Update to use new extension methods inferring java class
Update the use of implied JSonCreator

Updates for 2.5.x and adding an implied JsonCreator when it is appropriate.

back-porting 2.5 changes

update tests to use the new type inference extension methods