Allow LoopBack applications to configure multiple User models and share
the same AccessToken model.
To enable this feature:
1) In your custom AccessToken model:
- add a new property "principalType" of type "string".
- configure the relation "belongsTo user" as polymorphic,
using "principalType" as the discriminator
2) In your User models:
- Configure the "hasMany accessTokens" relation as polymorphic,
using "principalType" as the discriminator
When creating custom Role and Principal instances, set your
User model's name as the value of "prinicipalType".
9fe084fffd