Do multi update when setting has_many to empty.

[ fix #2527 ]
Fix warnings
Dup aliased_fields on subclasses.

[ fix #2528 ]
Fix default field override in subclass.

This allows the subclass of a parent document to redefine a field of the
same name, where the default in both is a proc. Previously the child
would ignore defining the default method again.

[ fix #2529 ]

Conflicts:
	spec/mongoid/fields_spec.rb
Ensure identity map is cleared with error [ #2445 ]
Debugger doesnt work with latest 1.9.3
Revert back to original middleware [ #2445 ]
Remove the proxy
Attempt to fix dowcasting when the document is persisted.
Rework specs and impl for #2541, update changelog

Conflicts:
	spec/mongoid/document_spec.rb
Add embedded docs using store_as to aliased fields. [ fix #2542 ]
Bump version
Only disconnect session on initialization if mongoid is configured. [ fix #2548 ]
Update changelog
Update version
Raise InvalidPath error when embedded access root paths.

[ fix #2552 ]
Preventing a NoMethodError when calling #as_document on an embedded relation that is nil.
Dont need the brackets
Fix broken spec
Remove default :blank error message from locale

Mongoid sets a default :blank error message in it's locale file. This is
confusing when trying to override error messages within your own app as
every overriden message will work except :blank.