Add has-many support for BasicAdapter
Pass has-many data to basic adapter hooks
Basic saving
Do not allow setting to essentially read-only setters

If you set to any of the essentially read-only computed properties
such as: isLoaded, isReloading etc... on model, you are going to have
a really bad time.
Improve error message

`fixture` is an instance of `Object`.

Before:
```
the id property must be defined for fixture [Object object]
```

After:
```
the id property must be defined for fixture {"foo": "bar"}
```
Use `toString` if environment doesn't support `JSON.stringify`
Fix docs for Adapter's map API
Update to 'relationship' terminology
Remove unused var declaration
Remove unused variables and helper functions
Documented the feature.