DATAMONGO-893 - Converter must not write "_class" information for know types.

We now actively pass on property type information to MetadataBackedField to ensure type hints get picked up correctly when converting a value to the according DBObject.

This has to be done as the fix for DATAMONGO-812 enforced proper writing of _class information for Updates, which caused trouble when querying documents by nested (complex) properties using an 'in' clause.

Original pull request: #169.
DATAMONGO-912 - Consider custom conversions in all stages of an aggregation pipeline.

We now consider custom mongo conversions in all stages of an aggregation pipeline. Previously we did this only for the first stage and returned object basically unmapped in later stages. We now pass the root AggregationOperationContext on to nested ExposedFieldsAggregationOperationContexts so that those can delegate any mongo Mapping to the root context.

Original pull request: #170.
DATAMONGO-914 - Improve resolving of lazy-loading proxies for classes that override equals(…)/hashCode().

We now properly resolve lazy-loading proxies for @DBRef's when an overridden equals or hash code method is called with Spring 4. We fall back to our old Objenesis proxy generation in order to circumvent the default handling for overridden hashcCode() and equals(…) methods in CglibAopProxies generated by Spring 4.

If we detect that we run with Spring 4 we use the repacked Objenesis that is included in Spring 4. Previously the generated proxy used some generic hashCode() or equals(…) logic that did not trigger a proper lazy loading in such cases.

Original pull request: #171.
DATAMONOG-899 - Overhaul index creation.

Prepare issue branch.
DATAMONGO-899 - Ensure proper creation of index structures for nested entities.

Index creation did not consider the properties path when creating the index. This lead to broken index creation when nesting entities that might require index structures.

Off now index creation traverses the entities property path for all top level entities (namely those holding the @Document annotation) and creates the index using the full property path.

This is a breaking change as having an entity to carry the @Document annotation has not been required by now.

Original Pull Request: #168