Add proposed Factorizing JSON Diff implementation

New files committed to branch for your review:

new file:   src/main/java/com/github/fge/jsonpatch/JsonFactorizingDiff.java
new file:   src/test/java/com/github/fge/jsonpatch/JsonFactorizingDiffTest.java
new file:   src/test/resources/jsonpatch/factorizing-diff.json

Test case data includes all tests from diff.json with added tests that highlight factorized move operations. There are also a few minor differences in generated patch operations for the tests common to both data files. Compare factorizing-diff.json to diff-json to review.