Embedded paranoid document deleted scope fixed.

[ fix #2451 ]
Don't fail on embedded pagination out of range

When skip or limit criteria are provided to an embeds_many relation
criteria that is out of range of the documents, we should simply return
an empty array.

[ fix #2476 ]
Removing indexes always uses strong consistency. [ fix #2485 ]
Store find params in DocumentNotFound errors. [ fix #2482 ]
Handle batch state passing in M/R aggregations

Mongo batches reduce jobs in groups of 100 and passes the state along
via the first document each time in the reduce function. This was
causing the count in the aggregations to reset every 100 documents that
were passed through the reduce. The effect would throw off any
calculations for avg and count with result sets larger than 100 docs.

[ fix #2482 ]
Fix changelog for #2481
Fix versioning of localized fields.

[ fix #2483 ]
Dont need the pid anymore in the database_id
Detach 1-1 unloaded relations properly. (Kostyantyn Stepanyuk)

[ fix #2474 ]
Adding in test middleware for #2445
Support Rails streaming in middleware.

[ fix #2445 ]
Remove unnecessary merge in cascading children.

[ fix #2491 ]
All explicit atomic ops now support field aliases.

[ fix #2494 ]
Update changelog
[ WIP ] Delay removal to docs to post validation.

First part of solving #2367 although we still have broken other specs
now with the first part of the fix.
Fix removal on embedded document via nested attrs.

Previously, embedded documents would get removed from the relation on a
nested attributes delete immediately, which would cause issues if the
parent document validation failed. Now these removals are delayed until
the parent passes validation and goes to persist.

Note this is a behaviour change, but since the API does not change and
the previous behaviour was incorrect and did not match AR this was able
to go into a point release. But it is worth nothing for those expecting
the old behaviour and hacking around it - they can remove the
workarounds at this point.

[ fix #2367 ]
Configure method documentation fixed
Model#becomes properly keeps the same id. [ fix #2504 ]
fixing broken check for updated_at in cache_key: issue #2501
Update changelog