Update changelog for 2.1.0

CHANGELOG.md

 # paranoia Changelog
 
+## 2.1.0 (2015-01-23)
+
+### Major changes
+
+* `#destroyed?` is no longer overridden. Use `#paranoia_destroyed?` for the existing behaviour. [Washington Luiz](https://github.com/huoxito)
+* `#persisted?` is no longer overridden.
+* ActiveRecord 4.0 no longer has `#destroy!` as an alias for `#really_destroy`.
+* `#destroy` will now raise an exception if called on a readonly record.
+* `#destroy` on a hard deleted record is now a successful noop.
+* `#destroy` on a new record will set deleted_at (previously this raised an error)
+* `#destroy` and `#delete` always return self when successful.
+
+### Bug Fixes
+
+* Calling `#destroy` twice will not hard-delete records. Use `#really_destroy` if this is desired.
+* Fix errors on non-paranoid has_one dependent associations
+
 ## 2.0.5 (2015-01-22)
 
 ### Bug fixes