allows custom `settings` for rest adapter's _ajax
Merge pull request #250 from joyshieh/master

Updates reference and referenceCache when model primary key changes.
Fix word in readme.
Merge pull request #253 from gunn/patch-1

Fix word in readme.
Merge pull request #241 from heartsentwined/overridable-ajax-settings

allows custom `settings` for rest adapter's _ajax
update ajax() signature to match _ajax()
Merge pull request #257 from heartsentwined/ajax-signature

update ajax() signature to match _ajax()
Fix dirty tracking test to compare Dates.
Serialize attrs before comparing for dirty tracking.
Merge pull request #264 from karenliu1/karen/dirty-tracking-attrs

Karen/dirty tracking attrs