InANutshell code used in the README
Introduce generic interface for JsonMutator and implement string mutation with a delegating implementation of that generic interface.

This interface allows adaptors to be written that are mutators of the object models of other Json APIs.
Move currying of function argument of JsonPath::map into the JsonPath class, meaning that the ElementAtPathMutation class is no longer required.

Also added a ReorderObjectProperties mutagen.
Merge remote-tracking branch 'origin/master'
Updated README