You can try with WildFly 8 alpha2 which has RESTEasy 3.0.1 already bundled.
Oterwise did you folow docs about upgrading RestEasy in AS7 http://docs.jboss.org/resteasy/docs/3.0.1.Final/userguide/html_single/index.html#upgrading-as7
there are modules provided in distribution that you should put in your AS7 modules directory...