Added test for model.changedAttributes()
Merge pull request #2518 from wecc/model-changed-attributes-test

Added test for model.changedAttributes()
[BUG] Transform `{NaN,Infitity,-Infinity}` to null

https://github.com/emberjs/data/pull/2509#discussion_r20898264

Serializing and Deserializing invalid numeric `JSON` (`NaN`,
`Infinity`, `-Infinity`) should result in `null`.
add test for no attribute type

from http://emberjs.com/guides/models/defining-models/:
"If you don't specify the type of the attribute, it will be whatever was
provided by the server. You can make sure that an attribute is always
coerced into a particular type by passing a type to attr:"
Merge pull request #2522 from kellyselden/add-no-attribute-type-test

add test for no attribute type
add test: FixtureAdapter doesn't save hasMany records

This failing test proves a bug exists when a record is created in the
store with a hasMany relationships. The relationships are simply lost upon
`phones.createRecord('name', {person: tom})`, where `tom` is the record
that has `phones`.

closes #1606, closes #1750
Merge pull request #2526 from sly7-7/fixtures-hasMany

add regression test: FixtureAdapter correctly save hasMany records
use defaultValue without supplying type

I prefer to use `DS.attr()` without a type when possible, but when I
want to use a defaultValue, I must supply a type. This would make it so
that you can supply a defaultValue, but still have an attribute without
a transform.
Merge pull request #2524 from kellyselden/use-default-value-without-type

use defaultValue without supplying type
Cache relationships meta in production