Set version to 1.12

Introduce OmitOperation

Code review changes:
- Reintroduce old JsonPatch.fromJson API
- RegistryBasedJsonPatchFactory
- Don't default operations upon construction of RegistryBasedJsonPatchFactoryBuilder
- Rename RFC6902* -> Standard*
- Other minor changes

Made a few changes to help a client easily integrate with the new extended functionality:
- Fixed bug where defaultFactory wasn't initialized
- Added extendedFactory
- Tests for the above

More code review changes:
- Created *OperationFactory classes
- Minor style changes
- made some things final

Converted JsonPatchOperation to interface, and got rid of a duplicate specification of operation names

Standard update to build files