add count to relations

Signed-off-by: Jaka Hudoklin <jakahudoklin@gmail.com>
Allow partial list of ids for sortByIds
Remove redundant test
Merge pull request #212 from offlinehacker/relations_count

add count to relations
Merge pull request #219 from fabien/fix/relation-tests

Fix  BelongsTo.prototype.create + remaining issues with new relation types
Merge pull request #222 from fabien/fix/relation-tests

Fixed duplicate code
Allow partial list of ids for sortByIds
Remove redundant test
Moved DataAccessObject.sortByIds to utils.js
Fix conflicts
Add strict flag to sortObjectsByIds

When true, any object not in the ids will be discarded and a subset
will be returned.
Merge pull request #216 from fabien/fix/sorty-by-id

Allow partial list of ids for sortByIds
Fix the test cases to avoid hard-coded ids
Bump version
Merge branch 'release/2.4.0' into production
Merge tag 'v2.4.0'

2.4.0
Check null

See https://github.com/strongloop/loopback-datasource-juggler/issues/223
Bump version
Merge branch 'release/2.4.1' into production
Merge tag 'v2.4.1'

2.4.1