[ja] Sync with 5ed1013ec42d2c92b7226b5f2130110b8d8caf78

Description of method assertJsonFileEqualsJsonFile was not corrent and was written in exact opposite way.
[ja] Sync with d6b807efbfcc5da3c6160fa1bb6f9959247882f9

Description of method assertJsonStringEqualsJsonFile was not corrent and was written in exact opposite way.
[ja] Sync with a6c9668ae747b2df95955d24f53567de4ea0e3a8

Description of method assertJsonStringEqualsJsonString was not corrent and was written in exact opposite way.
[ja] Sync with 2f7560b3e94e3cff65e0be56b0c78f2bb5bb570f

There was a typo in assertContainsOnly method description.
The typo was 'actual value' which should have been 'haystack' instead.
[ja] Sync with 921fd733d24f846ecec488de2d507a77d3d7a6de

Sync #85 and cleanup.