Fix: optimization bugs #55, #54, add more tests

[mrhadenough]

Also added tests from https://github.com/talentdeficit/json/blob/master/json-patch-tests/tests.json

[coveralls]

Coverage increased (+1.6%) to 96.049% when pulling d1f317a on mrhadenought:fix_optimization_bugs into 27f1f98 on stefankoegl:master.

[coveralls]

Coverage increased (+1.6%) to 96.049% when pulling 05d9ace on mrhadenought:fix_optimization_bugs into 27f1f98 on stefankoegl:master.

[coveralls]

Coverage increased (+1.6%) to 96.049% when pulling 05d9ace on mrhadenought:fix_optimization_bugs into 27f1f98 on stefankoegl:master.

[stefankoegl]

Thanks! I have released 1.16 containing your pull request.