hasOne relations aren't found in store for newly added records

[zuzusik]

Description

Environment

• js-data version: latest
• node or browser version: any
• operating system: any

Steps to reproduce

try adding records to store which have hasOne relation and there are already related records in store - related records won't be linked to newly added records

Cause

The implementation of findExistingLinksFor is incorrect for hasOne relation:

js-data/src/Relation/HasOne.js

Line 5 in c068c4b

findExistingLinksFor (relatedMapper, record) {

where it's being called like this:

js-data/src/Relation.js

Line 146 in 65a2a78

relatedData = this.findExistingLinksFor(record)

so, as it's seen - first argument should be a record, and second argument even never passed

to compare, this is the impl of this method for hasMany:

js-data/src/Relation/HasMany.js

Line 43 in 17020d8

findExistingLinksFor (record) {