Add documentation for ":on" option, to limit which actions are audited.
Update README to better document strong_parameters requirements.
Update README.md

Fix small 'wihtout' typo
Merge pull request #174 from punnie/patch-1

Update README.md
Merge pull request #150 from xevix/master

Add documentation for ":on" option, to limit which actions are audited
Merge pull request #151 from covermymeds/document-strong-parameters

Update README to better document strong_parameters requirements.