Add ability to skip validation of a method by honoring @SkipValidation
Per the Struts2 documentation, if an action is model driven, validation
will be preformed on the model instead of the action.

Refer to:
http://struts.apache.org/release/2.3.x/docs/model-driven.html
Merge pull request #3 from apexcapital/master

Add ability to skip validation of a method by honoring @SkipValidation