DATAMONGO-1077 - Fix Update removing $ operator for DBRef.

We now retain the positional parameter "$" when mapping field names for associations.

Orignal pull request: #235.
DATAMONGO-1076 - Avoid resolving lazy-loading proxy for DBRefs during finalize.

We now handle intercepted finalize method invocations by not resolving the proxy. Previously the LazyLoadingProxy tried to resolve the proxy during finalization which could lead to unnecessary database accesses.

Original pull request: #234.
DATAMONGO-1080 - AbstractMongoQuery now refrains from eagerly post-processing the query execution results.

To properly support general post processing of query execution results (in QueryExecutorMethodInterceptor) we need to remove the eager post-processing of query execution results in AbstractMongoQuery.

Removed the usage of the local ConversionService all together.
DATAMONGO-1078 - @Query annotated repository method fails for complex Id 

Prepare issue branch.
DATAMONGO-1078 - @Query annotated repository method fails for complex Id when used with Collection type.

Remove object type hint defaulting.