package in audit
This PR implements reputation store and replace overlay in audit service
to use such store for storing node's audit stats.
In order to keep the changeset smaller, most of the changes in this PR is for copying audit logic in overlay to
reputation package. In a following PR, the duplicating code will be
removed from overlay.
Change-Id: I16c12494a0970f44c422b26cf603c1dc489e5bc1
