Gid rid of rspec deprecation warnings
Fix _destroy check on nested attributes.

When passed an array, only on a 1-n situation with nested attributes,
the attributes were not properly getting converted to a hash with
indifferent access.

[ fix #2911 ]
[ close #2912 ]
Fix deprecations in sessions spec
Don't memoize collection_name and database_name.

[ fix #2893 ]
[ fix #2857 ]
Enable public-facing dirty attribute methods to cope with field aliases

Changeable uses db field names internally but should also be able to handle
aliases given to its public-facing methods.
Update changelog
Fix chaining nil scopes
Ensure setters always return set value.

[ close #2603 ]
Move rvm to 2.0.0 by default
Adding aliases to serialization [ #2716 ]