Unable to create `between` relationship in create entity call

### Problem Creating an entity along with a between relationship in a single POST call is not working. ### Reproducing Consider these sample entities and relationship: ``` (entity :Resource {:Id :Identity :FullName :String}) (entity :Team {:Id :Identity :Name {:type :String :unique true}}) (relationship :TeamResource {:meta {:between [:Team :Resource] :one-many true}}) ``` First create a Team: ``` POST /api/ResourceAllocation.Core/Team { "ResourceAllocation.Core/Team": { "Name": "My Team 1" } } ``` Then, create a Resource while creating the between relationship at the same time: ``` POST /api/ResourceAllocation.Core/Resource { "ResourceAllocation.Core/Resource": { "FullName": "Roe" }, "ResourceAllocation.Core/TeamResource": { "Team": "{{teampath}}" } } ``` It will create Team, Resource correctly but will not create the relationship. It used to work on previous version before (possibly) interpreter rewrite.