NUTCH-1533 - Implement getPrevModifiedTime(), setPrevModifiedTime(), getBatchId() and setBatchId() accessors in o.a.n.storage.WebPage

git-svn-id: https://svn.apache.org/repos/asf/nutch/branches/2.x@1460380 13f79535-47bb-0310-9956-ffa450edef68