RAVE-999, RAVE-1000. Add ResourceRepository Interface for common methods needed for rest resources. Implemented on PageRepository, following model of widgetrepository.

git-svn-id: https://svn.apache.org/repos/asf/rave/trunk@1507343 13f79535-47bb-0310-9956-ffa450edef68
Actually commit interface

git-svn-id: https://svn.apache.org/repos/asf/rave/trunk@1507344 13f79535-47bb-0310-9956-ffa450edef68