Rails 4.1 compatibility & commits from other forks

Hi there. Nice to know that paranoid repository is gonna be actively mantained again.
There were some commits by other folks in defferent branches ([twonegatives](https://github.com/twonegatives/acts_as_paranoid), [goodwinproject](https://github.com/goodwinproject/rails3_acts_as_paranoid), [gazay](https://github.com/gazay/rails3_acts_as_paranoid]), [byroot](https://github.com/byroot/rails3_acts_as_paranoid)) during the inactivity time.
These commits add Rails 4.1 compatibility and fix some known issues.