Updated ModelToIdPropertyTransformer so it works with Entities which implement \ArrayAccess
Added FooArrayAccess class to allow testing of new code
See #2301
Updated logic and added Exception messages when an incorrect configuration is used.
Merge pull request #2302 from caponica/fix_transformer_array_access_entity

Fixed problem with ModelToIdPropertyTransformer and ArrayAccess entities
Merge remote-tracking branch 'origin/master'