v2.12.0
Merge branch 'release/2.12.0' into production
Merge tag 'v2.12.0'

2.12.0

 * Relax the id comparison (Raymond Feng)

 * Allow more flavors of nullable values from DB discovery (Raymond Feng)

 * Fix a typo (Raymond Feng)

 * docs.json: add lib/model.js (Miroslav Bajtoš)

 * Update README.md (Rand McKinney)

 * fix embedsOne error when embed instance is undefined or null (Clark Wang)

 * Be explicit: set RelationDefinition multiple flag (Fabien Franzen)

 * Allow hasOne relation to have a scope option (Clark Wang)

 * fix skipping async validator will always fail if condition is un-fulfilled (Clark Wang)