Merge tag 'v2.4.1'

2.4.1
Properly handle LDL for polymorphic relations
Properly handle LDL for polymorphic relations
Merge branch 'fix/ldl-polymorphic' of github.com:fabien/loopback-datasource-juggler into fix/ldl-polymorphic
Tiny fix: obsolete i8n require
HasMany exists should use internal findById

This limits the scope correctly, taking polymorphics into account.

(the foreign key check is actually obsolete I think)
Merge pull request #225 from fabien/fix/has-many-exists

HasMany exists should use internal findById
Merge pull request #224 from fabien/fix/ldl-polymorphic

Properly handle LDL for polymorphic relations
Add ability to apply a plugin multiple times from LDL
Fix ModelDefinition toJSON bug
Merge pull request #227 from fabien/fix/definition-tojson

Fix ModelDefinition toJSON bug
Merge pull request #226 from fabien/feature/multi-mixin

Add ability to apply a plugin multiple times from LDL
Prevent failure with null in List toObject
Merge pull request #228 from fabien/fix/list-to-object

Prevent failure with null in List toObject
Bump version
Merge branch 'release/2.4.2' into production